1. Summary
2. What is the isometric mid-thigh pull (IMTP)?
3. Why is the IMTP important?
4. How do you perform the IMTP test?
5. How to collect IMTP data?
6. Are there any issues with the IMTP?
7. Is future research needed with the IMTP?
8. Conclusion
9. References
10. About the Author

Summary

The isometric mid-thigh pull (IMTP) test is an effective and reliable way to test maximal strength in youth and adult athletes. Research has shown that performance variables from the IMTP test correlate to athletic movements such as the vertical jump and sprint speed.

Administering the IMTP test is a safer and more time-efficient method than traditional 1RM testing which also benefits athletes with a low training age. The IMTP and use of isometrics can be used in a training programme to effectively develop strength, power, and tendon stiffness.

When administering the IMTP test, the protocol needs to be standardised to ensure the most reliable data possible.

What is the isometric mid-thigh pull (IMTP)?

The isometric mid-thigh pull (IMTP) test is a multi-joint exercise designed to assess the strength and force production capabilities of an athlete’s entire body. As stated in the name, the exercise is isometric in nature, meaning the bar is fixed in place and does not move.

A maximal isometric action allows individuals to produce a greater force than a maximal concentric action. For this reason, IMTP is often used to measure maximum strength [1, 2] in both research and by strength and conditioning coaches. The IMTP requires an individual to pull on a fixed barbell with a maximal effort for 3-5 seconds. When performed on top of a force plate, the test can quantify peak force, relative force, rate of force development (RFD), time to peak force, etc.

Why is the IMTP important?

The IMTP assesses performance qualities that are critical to most sporting actions such as strength and power. Research has found a correlation between maximum strength and sprint speed [3, 4], along with the rate of force development and vertical jump performance [5, 6]. Data retrieved from the IMTP can be combined with other tests that give coaches valuable information such as the Dynamic Strength Index. Khamoui et al. [5] investigated dynamic strength and concluded that explosive isometric force production within the first 100 milliseconds correlated with vertical jump height. This suggests that isometric capabilities have velocity and time characteristics transferable to sporting actions.

The IMTP is a safer and more time-efficient alternative to one-repetition maximum (1RM) testing. Performing the IMTP requires a low training age and is safe to perform since the test does not put individuals in compromising body positions. S&C coaches who have athletes with a low training age may not feel comfortable with their athletes testing with heavy loads. Performing a 1RM test may cause individuals to break technique, this can be counter-productive for coaches who are still installing good movement patterns in their athletes.

The test is also time-efficient since performing the IMTP lasts only 3-5 seconds. Building up to a 1RM can take upwards of half an hour for a single athlete, whereas the IMTP allows coaches to assess multiple athletes within a short period of time.

Little research exists on the IMTP test within younger populations, however, the test can be administered to both youth [1] and adult athletes [7]. Moeskops et al. (2018) [8] established that the IMTP test is reliable in measuring peak force in pre- and post-peak height velocity youth athletes. With youth sports becoming more competitive, being able to quantify strength in young athletes can give a performance and injury-risk advantage. For this reason, youth athletes should also train maximal strength.

Brownlee et al. (2018) [1] used the IMTP test to assess differences in strength during the season with youth football athletes who regularly participate in strength training. No changes in maximum force were found, indicating the training received did not make the athletes stronger, possibly due to not being exposed to a great enough intensity. For this reason, the IMTP can be used as both a training method for maximal strength in youth athletes and as an in-season monitoring tool.

Another benefit of the IMTP is that it mirrors the positioning of the second pull in the clean & jerk weightlifting movement, which many consider to be where the most power is developed in the lift. Olympic weightlifting is undoubtedly an effective way to increase power production in athletes [9]. The IMTP also has viability as a training exercise in the weight room.

Isometric training has gained popularity with many S&C coaches for multiple reasons. For one, isometrics can be performed at multiple angles and train ‘weak points’ in athletes by allowing them to produce as much force as possible in a range of motion they are unable to. Anecdotally, this has helped many powerlifters and may also benefit dynamic sport athletes.

Secondly, isometric training provides variability to athletes performing conventional concentric and eccentric training. Isometrics can also provide a greater intensity to training without the fatigue brought on by loaded repetitions. Finally, isometric training can increase tendon stiffness within the lower limbs when performed regularly [10].

Video 1 – Demonstration of the IMTP test by Innervations

How do you perform the IMTP test?

The IMTP requires individuals to pull on the bar with maximum effort for a continuous 3-5 seconds. Administration of the IMTP test requires a standardised protocol to get the most reliable data.

Required equipment

• Force plate that can record at 1000 Hertz (Hz)
• A barbell that can be adjusted to different heights, including a way to secure the barbell to disallow movement.
• Performance recording sheet

The individual being tested should be sufficiently warmed up and be familiarised with the protocol. Body positioning is critical during the IMTP and can affect the outcome/data produced. Dos’Santos et al. (2017) [11] reported that hip angle significantly affects peak force and RFD, with a hip angle of 145° recommended as optimal. Two practice trials of the IMTP before recording will help prevent intra-individual errors.

The barbell must be placed at the height of an individual’s mid-thighs when they are in a slight Romanian deadlift (RDL) position. Secondly, the athletes should be educated on your cues as well as the signal for when to start the pull. Cueing is important and can help produce the best results from your athletes. Test administrator cues should be concise, sharp, and consistent whilst avoiding over-explanation. Here’s an example of the cues I give when administering the test:

• Step onto the force plate with thighs touching the bar.
• Wrap your hands around the bar without pulling.
• Shoulders back. Chest up. Look straight ahead.
• 3, 2, 1, PULL!

Testers should be experienced with the software being used to calculate the IMTP. A minimum baseline of 1-2 seconds is usually required in most software before the start of a pull. During this time the athlete should be standing completely still before the start of their pull. This allows time-dependent variables such as RFD and time-to-peak force (TPF) to be measured accurately. Let athletes rest between 1-2 minutes between trials.

In the video below I show you how you can use a £35 crane scale to measure IMTP and also collect the data using our free IMTP scoring spreadsheet.

How to collect IMTP data?

If you’d like to start testing your athletes’ strength and power using the IMTP, then you’ll need a spreadsheet which helps you collect and analyse all of the data. Luckily for you, we created a simple and easy-to-use IMTP scoring spreadsheet which allows you to do just that. You can download our free IMTP scoring spreadsheet via the box below.

Are there any issues with the IMTP?

The main concern with the IMTP is the equipment needed to perform the test. Most coaches do not have access to a force plate which allows them to measure peak force and RFD. Similarly, the setup required for the IMTP can take some time depending on the equipment on hand or the limitations of a gym.

Recently, RFD in the IMTP test has been shown to correlate with sprint acceleration [12]. However, the IMTP measures the ability to produce force primarily in the vertical direction. The variables taken from the IMTP may have a limited transfer to horizontal, frontal, and transverse plane movements. While performance was carried across a different force vector in the Townsend [12] study, isometrics in a more specific direction may be more valid since most sports are played in multiple vectors.

During an IMTP test, a countermovement action may be present on a force trace between the end of a baseline and the onset of the pull (Figure 1). This affects the reliability of the IMTP variables because it means the individual used the stretch-shortening cycle (SSC) to their advantage to produce more force. While the SSC is evident in athletic movements, this movement during testing can vary greatly which inherently makes the testing variables less reliable.

Familiarisation is needed with all participants performing the IMTP for the first time. Moeskops et al. (2018) [8] reported that pre-peak height velocity athletes require multiple familiarisation trials before producing reliable peak force, RFD, and time-to-peak force. Older athletes unfamiliar with body positioning and with a low training age may also need multiple familiarisation trials.

Is future research needed with the IMTP?

A plethora of research on the IMTP already exists. Some interesting areas and directions into this research topic include:

• Using the single-leg isometric mid-thigh pull to assess lower-limb asymmetries.
• A horizontal isometric pull/push test.
• Acute effects of short-term isometric-only training on vertical jump performance.

Conclusion

The IMTP is a reliable and valid test for measuring maximum strength in both youth and adult athletes. In research, the test provides sports scientists with critical information such as peak force and RFD. For coaches, the use of the IMTP and isometric training may increase strength and power development without fatiguing muscles. Coaches may use this as an alternative to 1RM testing because it is both safe and time-efficient. Also, the IMTP can be used to assess/monitor maximum strength during the in-season.

When administering the IMTP, testers should be confident in their protocol and standardise their methods to avoid error and reliability issues.

The post Isometric Mid-Thigh Pull (IMTP) appeared first on Science for Sport.

1. Summary
2. What is growth?
3. Why is monitoring growth important?
4. How do you monitor growth?
5. Are there any issues with monitoring growth?
6. Considerations for monitoring growth
7. Conclusion
8. About the Author
9. References

Summary

All humans experience growth during the early stages of life. For youth athletes, body composition and size are often a predictor of strength and power when relative to chronological age. Sports performance professionals may find it useful to monitor anthropometrics, such as height and weight, in order to determine periods of peak growth within a child’s development.

Alternatively, it is just as critical to determine periods of stunted growth. A child experiencing normal growth relative to their age group is likely to be in good health, meanwhile, a child experiencing abnormal growth may have an underlying disease or hormonal problem, for example. Early identification of a growth problem should be made known to a medical professional. The earlier the detection, the more effective treatment can be for a child to assist with healthy development.

What is growth?

Growth is a natural and individual biological activity all humans go through, starting from conception up until adulthood. Noticeable changes can be seen in the body during the first 20 years or so of life. Bones and muscle tissue grow within our body parts which results in an increase in height and weight.

Physiologically speaking, growth is a multi-factorial process but happens due to a combination of hyperplasia, hypertrophy, and accretion [1]. These cellular processes drive growth in a non-linear path from childhood until adulthood [1]. We not only see growth in tissue, but also in behavioural, cognitive, and social characteristics.

Why is monitoring growth important?

Assessing a child’s height is a great indicator of their general health [2]. When a child experiences abnormal growth, this may indicate the child has a disease or health condition that can affect their final adult stature or wellbeing [2]. Early detection of abnormal growth allows for an appropriate medical diagnosis, and in some cases, may even be treatable [2]. The later a growth problem goes unrecognised/unreported, the opportunities for medical assistance for that child decreases.

Most countries have different standards for assessing short stature and abnormal growth which is relevant to their population. For example, in the UK, a child’s height below the 0.4^th percentile is assigned as severe short stature [3]. While in the Netherlands, severe short stature is anything greater than -2.5 standard deviations from the norm [4]. Although this accounts for a small portion of each country’s population, the fact remains that assessment of children’s height should be assessed against normative growth reference charts for identification.

In 2004, The World Health Organization (WHO) assessed the growth and development of young children all over the world [5]. Specifically, they studied 8,440 children from six countries of diverse cultural and ethnic backgrounds (Brazil, Ghana, India, Norway, Oman, and the USA) to more comprehensively understand growth. Their findings report that healthy children are more likely to reach their full genetic potential when living under healthy conditions which include: nutrition, BMI, breastfeeding, and parents refraining from smoking. While broad, this indicates that regardless of ethnicity, socioeconomic status, or type of breastfeeding, children can grow normally when living in optimal healthy conditions.

As alluded to previously, all children do not grow at the same rate, nor in a linear fashion. As a result, it is crucial that all sports performance professionals, understand if an athlete is growing at a “normal” rate, or if, for some reason, their growth appears to be “abnormal” (e.g. stunted). By measuring growth rates on an ongoing basis, the coach/practitioner will be able to identify if an athlete is experiencing a period of “abnormal” growth, and being able to do so could be vital for that child’s health and performance.

Though the coach/practitioner may be capable of identifying whether or not an athlete might be experiencing a period of abnormal (e.g. stunted) growth, they cannot, and should not, attempt to diagnose the issue themselves. Instead, the coach/practitioner needs to make an educated and strategic decision regarding the proceeding course of action; for example, notifying the parent(s) and/or a qualified medical practitioner.

The reason for this is simply because a child’s growth may be abnormal (e.g. stunted) for myriad complex reasons. Some of these may include:

• Genetic predisposition (e.g. Achondroplasia)
• Malnutrition
• Illness (e.g. thyroid disease)
• Endocrine disorders
• Injury (e.g. damage to the epiphyseal plates in bones)

In some cases, for example, the coach/practitioner may not want to inform the parent(s) directly as the issue could be the result of malnutrition which may have arisen from issues at the child’s home (e.g. domestic abuse). Collectively, all of this information highlights the severity and complexity of potential problems surrounding a child’s growth.

How do you monitor growth?

Monitoring growth is a simple and practical task that coaches can implement into training times. However, it may be unnecessary to do so every session. Collecting height and weight data every three months can provide a sufficient picture of the development of an adolescent athlete.

For validity and reliability purposes, the procedures for collecting the data should be similar every time it is performed and with the same equipment. For example, using the same weight scale and stadiometer each time can limit the variance of data. Also, wearing minimal clothing and removing shoes can provide a more accurate estimation of height and weight.

Anthropometric data from a child can be used to estimate adult stature. Predicted adult height can be estimated for individuals if information about the biological parents’ height is obtainable [6]. The equations for both genders can be seen below (Figure 1). Further work by Sherar et al. (2005) [7] concluded that using other anthropometric data such as weight, height, and sitting height to predict adult stature is accurate within 5-8 cm in boys and 3-8 cm in girls for 95 % of cases. The importance of this is that it can be combined with longitudinal growth and determine the percentage of predicted adult stature.

If you’d like to know more about predicting an athlete’s adult stature, then you can read our article on bio-banding and download your FREE adult stature prediction spreadsheet (named: Bio-Banding Calculator) which you can use right away with your athletes.

Click HERE to read the article and get your FREE Bio-Banding Calculator.

Are there any issues with monitoring growth?

Keeping longitudinal data on height and weight allows coaches to identify peak growth rates, only after they have already occurred. For this reason, monitoring growth on its own may not provide enough information for coaches, therefore, it is recommended that this is combined with other data to determine maturity offset (e.g. peak-height velocity (PHV)) or growth velocity.

Growth velocity is the rate of growth over time (millimetres per year (mm/year)) that young humans experience. A typical growth velocity curve shows fast growth in early childhood, then gradually slowing down until the start of the pubertal growth spurt (Figure 2). During the decline from infancy to late adolescence, it is not unusual for a young child’s height to be in the 95^th percentile one month and be in the 20^th percentile the next [2]. Human growth can be highly complex, which can make interpretation difficult.

This huge variation in growth should not be of concern unless an infant is assessed below the 5^th percentile in consecutive measurements over a period of 3-6 months [2]. If an athlete is referred to a medical practitioner for short stature, the physician will generally adopt a “wait and see” policy over a short period of time before recommending specialist advice or treatment [8].

Misdiagnosis of growth disorders and unnecessary referrals can arise from errors in height measurement or inaccurate plotting of values in a growth chart [2]. For this reason, it is critical to assess a child’s height consistently with the same reliable tools and methods. Also, having an appropriate growth chart can be an essential tool for surveillance of a child’s height.

Patterns of growth are different between genders after puberty [9]. Pre-puberty, body composition is similar between genders but changes at the onset of puberty due to more circulating androgens in boys compared to girls [1]. During the adolescent growth spurt, boys tend to experience greater increases in arm girth and shoulder width compared to girls [10]. Also, boys tend to have greater fat-free mass and about half the body fat percentage to that of girls at the end of the adolescent growth spurt. Meanwhile, girls tend to experience greater increases in hip width and fat mass compared to boys [1].

Considerations for monitoring growth

Monitoring growth is simply that – do not diagnose. If a child appears to fall out of the 5^th or 95^th percentile for growth at their age, the best thing to do may be to refer out to qualified medical practitioners (e.g. physician). Growth is multi-factorial and can be influenced by many factors such as genetics, malnutrition, or damage to the epiphyseal plates in bones.

As coaches, we should not overstep our boundaries and improperly diagnose athletes. Monitoring growth gives us critical information about the development of an athlete but does not reveal the underpinning factors that may cause it.

Conclusion

Monitoring growth is a valuable tool for sport performance professionals who work with young athletes. By collecting longitudinal data on height and weight, coaches can identify periods of peak growth and survey their athletes for normal development.

Coaches who identify children who fall outside of the normative height or weight values for their chronological age group should refer to qualified medical practitioners (e.g. physicians). From there, medical professionals can supply children with appropriate treatments which can optimise the possibility for good health, and development, and therefore towards reaching their optimal adult height.

The post Monitoring Growth appeared first on Science for Sport.

1. Summary
2. Why is practice important in sports?
3. What is neuroplasticity?
4. Why is neuroplasticity important for sport?
5. Are there any issues with neuroplasticity?
6. Is future research into neuroplasticity needed?
7. Conclusion
8. References
9. About the Author

Summary

Neuroplasticity refers to our brain remodelling, adapting, and organising after the practice of a motor skill; this is important for many professionals (i.e. coaches) in sport who teach and develop specific athletic skills with their athletes.

When learning new motor skills, there is a “fast-stage” and “slow-stage” of learning. Our brain tends to learn new motor skills quickly, then a plateau is reached at which more practice is needed to maintain that same motor skill. Research indicates that grey matter density in our brain is responsible for motor control and is mostly formed before puberty.

There is a window of opportunity for teaching children fundamental movement skills by taking advantage of the ‘plasticity’ of grey matter in their brain. This can result in beneficial outcomes later in life such as increasing athletic potential through greater movement competency. The best form of training for children appears to be integrative neuromuscular training, which focuses on developing various motor skills with an emphasis on technique. However, it is still possible to develop and strengthen motor skills after the brain fully matures, but this may be more difficult to achieve.

Why is practice important in sports?

Repetitive practice of motor skills is necessary to efficiently develop and refine movement in sport. Ultimately, our brain controls how we move via an electric signal sent to our muscles. The speed, accuracy, and efficiency of that signal is dependent on many factors, one of which includes practice. Our brain refines a motor neuron pathway the more we practice a skill, but will also reduce that same pathway if we fail to use it [9]. Simply put, we become more skilled at tasks we do often and can have that same skill “fade away” if we fail to practice it.

Teaching and refining athletic motor skills is an important aspect of a strength and conditioning coach’s job. When an athlete performs exercises in a weight room, they reinforce a neural pathway whether the movement is correct or incorrect. With every repetition, the motor neural pathway becomes stronger, and if done frequently, can lead to a significant change [7]. This phenomenon is due to neuroplasticity and our brain’s ability to adapt. This article will discuss neuroplasticity’s importance in sport and the implications of training different age groups.

What is neuroplasticity?

Neuroplasticity refers to the brain’s capacity to adapt and re-organise as we experience and learn different tasks [1]. The scope of neuroplasticity is large and complex, with different events occurring at the molecular, synaptic, and muscular levels over short and long periods of time. However, neuroplasticity can be understood by strength and conditioning coaches by grasping basic information about the topic. To begin, we must learn about the role of grey matter and how it relates to the ability to acquire and/or retain motor skills.

The importance of grey matter
Our brain and spinal cord contain grey matter (GM), which is responsible for motor control and sensory perception in our body. GM contains motor neurons that send action potentials down the axon and into our muscle cells, which results in movement [5]. There tends to be a stronger signal and more refined neural pathway when there is high GM density in the brain [5]. Studies indicate that humans tend to increase GM density during childhood, followed by a loss of GM density after puberty [3, 4]. It is suggested that as we mature, the volume of synaptic connections decreases and our ultimate GM density is determined [4].

An interesting study by Gogtay et al. (2004) [5] reports that following brain maturation, an adolescent’s GM density diminishes until young adulthood. However, this does not mean that we are unable to learn new motor patterns after puberty. Instead, it simply implies the greatest “window of opportunity” for learning motor skills is before puberty and that afterwards, motor skill pattern potential is limited due to the motor synapses closing.

Fast- and slow-stage learning
Changes in motor skill neuroplasticity are often divided into a “fast-stage” (short-term) and “slow-stage” (long-term). During fast-stage learning, it is believed the primary motor cortex in our brain recruits substantially more neurons for new motor tasks [6]. This increase in brain activity can result in vast improvements being seen within a single training session. After improving a motor skill, we transition to the slow-stage of learning where multiple training sessions and repetitive practice are needed to retain or improve that skill.

Unlike the fast-stage, the slow-stage of learning results in small improvements at a much slower pace [7]. This is due to neuroplasticity’s “use it or lose it” principle when it comes to motor skills [9]. The brain’s plasticity will either slowly strengthen or reduce a motor pathway based on repetitive action, or the lack thereof. However, past repetitive practice of motor tasks could lead to a quicker re-adaptation if there was stoppage of that skill [8]. This term is called “savings” and is why many athletes can still perform a skill such as shooting a basketball, even after years of not practicing.

One important thing to consider with fast-stage and slow-stage learning is that the acquisition of a skill is highly task-specific and relevant to the person. Generally, the learning curve of a motor skill will look the same when considering the specificity and difficulty of certain skills (Figure 2).

Learning basic squat technique can be done within one training session with some athletes. The Clean & Jerk, however, can take weeks of practice in order to become proficient due to the coordination needed to perform the exercise at high speed. Of the two exercises, the Clean & Jerk is a much more difficult motor skill to learn, and whilst it would be unfair to compare the two exercises hand-in-hand, it does provide a clear example of movement complexity, skill acquisition, and the different times needed to learn certain movements.

Why is neuroplasticity important for sport?

To proficiently perform athletic movements the brain must coordinate with the necessary muscle groups to produce the action. Whether the athlete is throwing a baseball, kicking a football, or even sprinting, these all require complex inter- and intra-muscular coordination which starts from the brain’s motor cortex. Therefore, repetitive practice is needed for a motor skill to be performed effectively, and thus engrained.

In most sporting competitions, athletes are at a disadvantage if they need to think before moving. Many people use the term “muscle memory” when they perform a skill automatically and without much thought. While incorrect, it does imply that a certain motor pathway is so well-developed that less brain activity and neuron organisation with the muscles is needed to perform a skill which before felt unaccustomed and alien. This is the reason why some skills tend to look or feel effortless after repetitive practice.

Due to neuroplasticity, every time a skill is performed our brain refines that motor pathway, regardless of whether it was performed correctly or incorrectly. For this reason, it is important to have coaches who promote correct technique, whether it be for the sport or in the weight room. If a bad movement pattern is performed repeatedly, the technique will require more practice and time to fix/refine. While neuroplasticity for sporting skills is achievable throughout our lives, research indicates that there is an opportune time to do so [9].

Neuroplasticity and Age
Plasticity in the brain appears to peak in pre-pubescent children, therefore, it may be the opportune time to capitalise on teaching correct technique/movement/skills [9]. By introducing multiple motor skills to young children, they have the unique advantage of maximising and enhancing muscular strength and fundamental sporting skills which may not be available as adults [10]. Training and exercise for young athletes should be specifically focused on improving motor control [11] since their cognitive and motor capabilities are highly “plastic” [12].

It has been suggested that integrative neuromuscular training (INT) be introduced during childhood and adolescent time periods to influence the plasticity of the motor cortex which will carry into adulthood [10, 13]. INT exercises expose children to a variety of movement patterns and challenges that promote cognitive and physical development [9, 13]. Proper introduction and implementation of INT, allows for physical, mental, and social development which will positively affect athleticism as the child grows [10]. If an athlete is not exposed to a certain motor skill prior to full motor cortex maturation, they are still capable of developing that skill, however, the benefit and potential are diminished [14, 15].

Neuroplasticity with regards to motor skills is available during a human’s entire lifespan but is best retained during all developmental stages (see Figure 1) [16]. Professionals who work in sport must implement training that teaches and reinforces good movement, regardless of age or training level. Much like the specific adaptations to imposed demands (SAID) principle in training, the motor cortex adapts in a similar way. Athletes should always be improving or refining their motor skills to maximise performance in competition.

Are there any issues with neuroplasticity?

Measuring ‘plasticity’ in an athlete’s brain is not worthwhile for strength and conditioning professionals for a few reasons. Examining neuroplasticity requires invasive and expensive equipment as imaging of grey matter and other regions of the brain requires access to an MRI machine and medical professionals to operate it.

Also, most research surrounding neuroplasticity in motor skills is not done in athletes, rather in individuals with movement disorders such as cerebral palsy [17], and animals [18]. Therefore, it may not be meaningful to quantify brain ‘plasticity’ in athletes, when instead the focus should be on teaching and refining motor competency.

Evidence suggests there are gender differences in the adolescent brain which can affect neuroplasticity [19]. Research has reported there is a higher ratio of GM to white matter in females [20] and that they may also reach peak values of brain volume earlier than males [19]. Similarly, it appears that the sex hormones testosterone and estrogen also have gender-specific effects on the organisation of brain structure during puberty which may affect its development [21].

The concept of neuroplasticity does suggest that repetitive practice of motor skills strengthens and refines movement competency. Many have heard of the 10,000 hours rule proposed by Malcolm Gladwell, which suggests this is the amount of time of deliberate practice needed to become phenomenal at a task [24]. However, this is often taken out of context and drives people to over-train and eventually burn out from exhaustion.

With neuroplasticity, there is a proposed concept of “offline training” which states that performance improvements of a skill can occur between training sessions with no further practice [7]. It is believed that this is due to a phenomenon in which the brain consolidates a movement pattern at the end of every practice which progressively stabilises the skill [22]. This results in an increase in accuracy, execution, and reaction of a motor skill due to rest.

“Offline” skill improvements can be affected by sleep [23], which ultimately demonstrates the importance of adequate rest/sleep. Therefore, mastery of a motor skill is likely to require a high volume of deliberate training with sufficient rest between sessions and adequate sleep.

Is future research into neuroplasticity needed?

To our knowledge, there have been no studies on neuroplasticity with a genuine strength and conditioning intervention. It would be interesting to see how motor skill competency can be influenced at all maturity stages, accompanied by an assessment of the brain’s GM via MRI. As such, the following areas of research are needed to expand current knowledge on this topic:

• The effects of INT on GM and neuroplasticity in children and adolescents.
• Gender differences in motor skill training and brain development following a 12-month movement competency programme.
• A longitudinal study: The long-term effect of INT on athletes as they mature from youth academy to professional athletes using MRI.

Conclusion

Neuroplasticity is a concept not well understood in the strength and conditioning realm but governs a big part of how athletes move and perform in sport. Understanding the basic concepts of neuroplasticity can help guide training programmes that focus on the importance of teaching and refining good movement. The brain’s plasticity appears to peak during childhood, and as such, professionals who coach young athletes should capitalise on this period of time by encouraging multi-skill development and educating correct movement, as this will likely have positive benefits that carry into adulthood.

The post Neuroplasticity appeared first on Science for Sport.

1. Summary
2. Introduction
3. What is maturation?
4. How does maturation affect sports performance?
5. How do you measure maturation?
6. What future research is needed on maturation?
7. Conclusion
8. About the Author

Summary

Maturation is simply the process of children growing and obtaining adult stature. All humans experience maturation differently, but we notice the greatest change after puberty. Females tend to mature sooner than boys, but post-pubertal boys will experience greater increases in strength and power due to testosterone and other androgen hormones.

An appropriate strength and conditioning programme will increase the motor skills, coordination, strength and power in children and adolescents. Adolescents may be prone to overuse injuries during periods of rapid growth in height and mass. Maturation should be measured in youth athletes to properly monitor their growth and well-being as athletes.

Research into the area of maturation (1, 2) and its impact on the performance of young athletes has recently gained popularity in the field of sport and exercise science. By now, many sport coaches understand that resistance training can have a positive effect on the health and performance of children and adolescents.

However, some may not know what is an appropriate strength and conditioning programme or how it can affect growth and enjoyment in sports. Having a basic understanding of the concepts related to maturation (e.g. motor development and injury risk) can assist coaches with managing their young athletes and preparing them for future success in sport.

What is maturation?

Maturation is quite simply the process of becoming mature (3). To understand maturation properly, we must realise that each child differs in the timing and tempo of this process. Timing refers to ‘when’ maturation begins, while tempo refers to the ‘rate’ at which it progresses.

We typically discuss maturation as the process from early childhood, to adolescence and then to full adult stature. Childhood is generally regarded as the time until which one reaches adolescence. The start of adolescence begins with the onset of puberty where hormonal and physical changes begin to occur (3). Initially, rapid changes begin to occur with increases in height, weight, stature and the development of secondary sex characteristics (3).

Up until puberty, there are few performance differences between genders (4). The adolescent stage usually begins sooner in girls (8-19 years) than in boys (10-22 years) (3), but up until puberty, there are few performance differences between genders (4). However, significant changes begin to emerge between genders after puberty due to circulating androgens (testosterone) (3). Testosterone causes boys to develop larger arm girth (5) and larger shoulder breadth in comparison to girls, while increases in hip breadth are alike (3). Similarly, during this rapid growth spurt, boys will have greater fat-free mass than girls and a smaller increase of body fat.

How does maturation affect sports performance?

Maturation plays a significant role in motor skill development, strength, power, and even impacts injury risk in young athletes. Understanding maturation and how it impacts youth performance is of great benefit to coaches and parents.

Research indicates that childhood is an ideal and opportunistic time in which to maximise motor skill proficiency (6-8). This is due to the natural and accelerative rate at which the brain (6) and central nervous system (9) mature in the child. Therefore, this vital time frame should be utilised by introducing children to a broad array of foundational movements, as well as exposing them to a variety of stimuli (10). If such foundational movements are developed before adolescence, it is believed that the athlete will be better equipped when faced with more complex motor skills during a later developmental stage.

As athletes reach adolescence and adulthood, they are less sensitive to developing new motor pathways (11), which therefore makes it more difficult to teach certain movement skills. As a result, youth athletic development programmes should be thoughtfully designed and carefully delivered in order to ensure the programme has maximal effect. Moreover, young athletes should be exposed to a range of different stimuli, however, this must not be delivered in a random or poorly thought-out format. Instead, the goal and focus of training sessions should be to develop gross athletic motor skill competencies (Figure 1) through a challenging and playful environment.

After puberty, strength increases develop differently between genders. However, it is important to understand that strength still remains trainable as children mature. As maximal strength seems to increase steadily for boys as they approach full adult maturity, girls tend to experience a plateau (3). It has been reported the gap between strength and power widens between genders in the years after puberty (4).

Despite this separation, both genders can expect significant increases in muscular strength and power following an appropriate short-term resistance training programme (12, 13). Having said that, this increase in strength is highly individualised as certain children respond more favourably than others (14). Resistance training can also bring about improvements in bone health (15), body composition (16), and self-esteem (17). Strength training produces many benefits for maturing children and may also provide implications for reducing injury.

Until recently, common thought outside of the sport and exercise community was that resistance training in children and adolescents was a major safety risk and detrimental to natural growth. However, it has been shown that children are much more likely to get injured during competition than they would be performing an appropriately delivered strength and conditioning programme (18). While exposure to strength and power is beneficial to the muscles, bones and soft tissue, they may still be at risk to overuse injuries.

Overuse injuries are a major problem for young athletes who are experiencing periods of rapid growth (19), and who are also being exposed to tremendous training loads. This can be brought about unintentionally by both sport coaches and practitioners who fail to recognise these important red flags (i.e. rapid growth and high training loads). Therefore, coaches who work with young athletes who are close to peak height velocity and peak weight velocity should consider their athletes’ growth rates, training loads, and levels of fatigue on a regular and ongoing basis.

How do you measure maturation?

While the timing and tempo of maturation differs for everyone, there are various methods to measure and accurately predict the growth of the human body. The best way to measure maturity status is through a radiograph of the athlete’s skeleton. However, this method is limited in its availability to coaches and large groups of athletes.

The next best method is by using the Mirwald equation (20), which is based on anthropometric ratio measures of the body. Specifically, the ratio of sitting height to leg length (20).

Genetics also play a huge role in estimating stature of a child. By using the height of both parents, you can calculate the mid-parent stature (21) of both boys and girls. If you wish to use this method, then click here to download your free bio-banding calculator so you can predict the adult height of your athletes and then group them based on their maturity.

Similarly, Sherar et al. (2005) (22) generated an equation to predict adult stature for adolescent boys and girls. A more pragmatic and traditional approach could be to regularly monitor the height and body mass of your young athletes. Three-month intervals should be a suitable interval time period at which you can monitor and detect rapid growth.

What future research is needed on maturation?

Although a lot is already understood about maturation, there is still far more to research and discover about this natural process. Such things include:

• How does maturation affect our ability to absorb and produce force in tests such as the drop jump?
• Does a strength and conditioning programme elicit hormonal responses in children that affect the onset of puberty?
• Does maturation timing and tempo affect or reflect sporting success as adults?

Conclusion

Maturation is simply the process of children growing and obtaining adult stature. This process is highly individualised, although there are distinct differences between genders after puberty. Children and adolescents should be exposed to a strength and conditioning programme that introduces them to a plethora of movements and motor skills.

There are several methods by which we can predict the stature of children as well as monitor them as they mature. Adolescents are at high risk for overuse injuries during times of extreme growth and high training loads; therefore, coaches should be extremely vigilant during these periods. Properly managing a child’s well-being during periods of maturation can support their health, assist their sporting success, and even promote their overall enjoyment of sport.

The post Maturation appeared first on Science for Sport.

1. Summary
2. Why is measuring force important in sports?
3. What is force-velocity profiling?
4. Why is force-velocity profiling important?
5. How do you perform force-velocity profiling?
6. Are there any issues with force-velocity profiling?
7. Is future research needed with force-velocity profiling?
8. Conclusions
9. References
10. About the Author

Summary

Force-velocity profiling is a simple and inexpensive way to assess an athlete’s force and velocity production capabilities during ballistic tasks such as jumping and sprinting. Through force-velocity profiling, a coach can identify whether an athlete is force- or velocity-deficient during a given movement (e.g. vertical jump), independent of their power capability. Based on the test results, targeted resistance training can then be implemented in order to reduce the athlete’s force or velocity deficiency, and improve their performance on that given task (e.g. vertical jump).

As a result, force-velocity profiling allows the strength and conditioning coach to tailor their athletes’ programmes more specifically by using detailed, objective information. Lastly, certain smartphone applications that require minimal set-up and provide instantaneous feedback can be used to assess the force-velocity profile of an athlete.

Why is measuring force important in sports?

The ability to produce high levels of muscular power is considered to be a vital component during many athletic and sporting activities such as jumping and sprinting (1, 2). Since power is the product of force multiplied by velocity (Power = Force x Velocity), it is therefore understood that these two components underpin the ability to be powerful.

Having said this, while two athletes may display similar power outputs, their force and velocity capacities may be markedly different. In theory, athletes are biased towards either strength (force) or speed (velocity), which may limit them in jumping (3) and/or sprinting movements (4). Therefore, measuring force and velocity – independent from power output – is useful for identifying whether an athlete is force- or velocity-deficient.

What is force-velocity profiling?

A force-velocity profile shows the relationship (curve) between the strength (force) and speed (velocity) of an athlete. Since power is a combination of force and velocity, the force-velocity profile also tells you something about athletic power (Power = Force * Velocity).

Force-velocity profiling (FVP) has gained popularity in recent years with both researchers and strength and conditioning coaches (4-10). Since the popularisation of FVP, multiple smartphone applications have been developed in order to identify an athlete’s force-power-velocity characteristics, and thus produce a theoretical FV profile. These applications are a simple way for coaches and researchers to measure an athlete’s force-power-velocity characteristics during a vertical jump or sprint.

This information can, therefore, inform coaches if an athlete is force- or velocity-deficient, as well as providing an optimal FV profile in which to work towards.

The principles of FVP are grounded by the Force-Velocity Curve, which if you are unfamiliar with, it is suggested that you read about the Force-Velocity Curve to better understand FVP.

As many coaches do not have access to expensive and complex laboratory equipment for which to test their athletes, FVP – via the use of smartphone applications – can provide a simple and inexpensive solution. FVP is often incorporated during performance testing sessions and can provide critical information to coaches if done periodically throughout a season.

Through profiling, coaches are provided with information regarding whether an athlete is force- or velocity-deficient in the given athletic task (e.g. jumping or sprinting). Furthermore, coaches are also provided with a theoretical and optimal FV profile, which can, therefore, allow them to implement training methods designed to target the deficiencies, and effectively optimise the athlete’s performance. This concept is better known as ‘targeted resistance training’.

FVP for Sprinting
The ability to accelerate, reach maximum velocity, and maintain it is critical during linear sprinting (5, 6). To understand FVP for sprinting, the horizontal force is an important concept to understand. In layman’s terms, and in regards to sprinting, the horizontal force is simply the force produced in the posterior direction as you sprint forward (5).

It has been reported the ability to produce horizontal force is a major factor during acceleration (8), as well as sprinting over longer distances (e.g. 100 m) (5, 6).

Although vertical force production peaks during maximal velocity, there is still a reliance on horizontal force production to move forward (6, 11, 13). Using FVP, a coach is able to calculate the ratio of force (RF) between vertical and horizontal ground reaction forces. During a sprint, this is calculated by dividing the horizontal force by the vertical force and measuring the slope at which the horizontal force decreases (5, 8).

Furthermore, the rate at which horizontal force declines is known as the rate of decrease in RF (DRF; Figure 2) (8). Whilst the loss in horizontal force production during sprinting cannot be entirely prevented, coaches can train the ability to sustain it and reduce the DRF (5).

FVP for Jumping
Optimal vertical jump performance requires one to accelerate their body mass to reach the highest possible velocity in the shortest time frame available (9). Vertical jump height is also a valid reflection of an athlete’s lower-body maximal power output (14). As a result, an athlete’s maximal power output (i.e. jump height) can be improved by either increasing their ability to produce high levels of force (strength training) and/or by improving their movement velocity with low loads (ballistic training) (15-17).

Put simply, improving an athlete’s force and/or velocity capabilities will likely result in an increased jump height (i.e. power output). However, determining which component an athlete is deficient in (i.e. force or velocity), is where FVP becomes of use.

When creating an FVP for a vertical jump, information on the ‘actual’ and ‘optimal’ profiles are provided. The ‘actual’ profile reflects the current force and velocity capacities of the athlete, while the ‘optimal’ profile is what should be worked towards in order to increase the athlete’s jump performance. The optimal FV profile is calculated using a validated equation by Samozino et al. (2012) and colleagues which includes the maximal power output and vertical displacement of the centre of mass (9, 18, 19) (Figure 3).

The difference between the actual and optimal profile is known as the ‘FV imbalance’ (FVimb). This measure represents the magnitude and direction to which there is either a force or velocity bias. Decreasing the FVimb has been shown to increase vertical jump performance in both force-deficient and velocity-deficient athletes (3).

Why is force-velocity profiling important?

Targeted resistance training based on individual FV profiling has been shown to be an effective method for improving vertical jump performance (3). In a recent study, 84 subjects were profiled as either velocity-deficient, force-deficient, or well-balanced. From there, subjects were broken into sub-groups of force-focused training (if velocity deficient), velocity-focused training (if force deficient), a general training group (if well-balanced), and a control group.

All groups performed nine weeks of targeted resistance training specific to their deficiencies, with the goal of reducing any FVimb. Both the force-deficient and the velocity-deficient training groups significantly increased vertical jump performance, while the results of the general training group and control group were highly variable and unclear. The conclusions from this study suggest that FVP can be used by coaches to tailor their training programmes more specifically to their athletes’ needs.

Whilst this article primarily focuses on sprinting and jumping, other ballistic-type movements, such as the bench press throw (20), can also be subject to FVP. A recent study on rugby union players assessed the force-power-velocity characteristics between forwards and backs during the bench press throw (20). The results indicated the forwards were stronger and more powerful than the backs, and that the backs were biased towards velocity. This information can, therefore, allow the coach to tailor training programmes specifically to the athlete’s weakness.

Another interesting aspect of this study was that players were ranked in each position based on their performance in the bench press throws. At the discretion of the coach, informing the players of their rank may help rectify their bias towards either force or velocity and motivate them to work on their deficiencies. Using a ranking system, and periodically testing FV characteristics, may also be a way of monitoring players with objective data.

How do you perform force-velocity profiling?

FVP is a simple process that requires minimal equipment. The jumping and sprinting tests require different variables which are outlined below. Using reliable and validated smartphone applications (21, 22), a coach can quickly and easily calculate variables such as optimal force, optimal velocity, FVimb, RF, and DRF.

The detailed methods/instructions for calculating FVP in sprinting and jumping can be found in the following studies (4, 8, 10, 18):

• Samozino et al. (2015)
• Morin et al. (2016)
• Samozino et al. (2014)
• Samozino et al. (2008)

How to FV profile maximal sprinting
In order to create an FV profile for sprinting, the following items are needed: body mass (kg), height (m), and either distance-time data or speed-time data (minimum five splits for a given distance) which can be obtained with timing gates (4). It is also recommended testing should be performed indoors to ensure a consistent surface, and to prevent any impact of wind speed and/or temperature. In addition, visible vertical poles are also required in order to mark the distance for different splits (e.g. 5, 10, 15 m).

To assess a sprint FVP, the RF and DRF must be fully understood. RF is the percentage calculated by the amount of horizontal force produced divided by the vertical force produced throughout a sprint. A higher RF throughout the sprint is considered desirable as it suggests the athlete is applying higher amounts of horizontal force. However, as speed increases, the RF (%) will inevitably decline – typically referred to as the DRF. A lower DRF is considered desirable as this implies that the athlete is better at producing horizontal force as velocity increases.

How to FV profile maximal jumping
In order to create an FV profile for jumping, the following items are needed: body mass (kg), standing height (m), jump height (m), and two lower-limb length measurements: 1) at fully extended position (m); and 2) with knees bent at 90° (m). A minimum of five separate jumps with an additional load for each jump is required to create a profile. To choose loads, there must be an even distribution of additional load starting from 0 % body mass to the last load at which the participant can jump about 10 cm with (8). For example, the five loads you may choose are body weight (BW), 15 % BW, 30 % BW, 45 % BW, and 60 % BW.

To assess a jump FVP, the FVimb between the ‘actual’ and ‘optimal’ jump profile must be fully understood. The distance and direction between the actual and optimal FV slope are referred to as the FVimb (Figure 3). A greater FVimb (%) suggests the athlete is biased towards either force or velocity (i.e. force- or velocity-deficient), depending on the direction of the slope. A lower FVimb is considered desirable as it suggests the athlete is well-balanced in producing both force and velocity. When an athlete demonstrates a high FVimb, decreasing the number is often the priority and can result in an improved vertical jump performance (3).

The equation used to calculate the FVimb (%) based on linear regression models of actual and optimal FVP is shown below (4, 9):

FVimb (%) = 100 (1 – FV actual / FV optimal)

The loaded jumps will provide a theoretical maximal force production value based on the loads used. Likewise, theoretical maximal velocity production will also be calculated based on the athlete’s time in the air during the jumps. With this information, the ‘actual’ FV slope can be calculated based on the loaded jumps, and from this, an ‘optimal’ FV slope can be calculated.

Are there any issues with force-velocity profiling?

Despite the promising concept and application of FVP, it does, however, still come with its faults. Some of these include:

• Linear regression: FVP uses linear regression to determine an optimal profile (23), however, it needs to be understood there is not a perfect correlation between force and velocity, despite linear regression assuming there is.
• Specificity: FVP is specific to the movement, and therefore, may not be specific to the sport. For example, a bilateral vertical jump is different from a lay-up jump in basketball. Optimal FVPs have been shown to be lower than actual FVP in world-class athletes (24). Chronic practice at a specific sport can create imbalanced FVPs, although this may not be limiting to performance (24) – take powerlifting, for example.

Is future research needed with force-velocity profiling?

Whilst there is emerging information and research supporting the efficacy of this testing and training method, it is very much in its infancy, and many more questions need to be answered. Some of which include:

• The effects of FVP on specific athletic populations.
• The effects of FVP on different ballistic-type movements (e.g. sled sprinting).
• How growth and maturation affect the FVP of young athletes around the period of peak height velocity.
• Whether FVP can be an effective tool to monitor performance and fatigue.

Conclusion

FVP is a useful tool for which strength and conditioning coaches can measure their athlete’s force and velocity capacities, independent of power. The optimal FV profiles generated can be used as training targets for the athletes in order to become more effective at jumping and sprinting.

It is important to understand the different variables associated with both jumping and sprinting. For example, with FVP in jumping, it is critical to decrease the FVimb in order to improve jump performance. Meanwhile, for sprinting, a lower DRF is desirable as it demonstrates the athlete is losing minimal amounts of horizontal force production as velocity increases.

FVP can be cost-effective, and can also be easily obtained using smartphone applications. However, like everything, FVP is not perfect and does have its limitations. It is not the be-all and end-all, but rather another tool that coaches can use to test athletes and perhaps programme more specifically. Having said this, coaches must decide if they feel there is enough value in this method in order to warrant its inclusion within the overall programme.

The post Force-Velocity Profiling appeared first on Science for Sport.