STATS AND DATA

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Every day people ask me if strength trackers are really useful, and what are the effects of their implementation in daily training sessions and over time. I usually talk about my experience as an athlete and trainer, on how I use Beast and the results I have reached. But I understand that the case of a single person and a few others are not enough to convince everybody.  From this observation was born the urgency to give the readers of this blog more scientific feedbacks. Even trainers usually don’t like talking about numbers and stats, as we are trainers not accountants, and what we love the most in training is the “dirty job” in the weight room; researches and science are fundamental and we cannot ignore them.

So this time I want to drive you in a kind of panoramic tour across some of the most significant researches in literature about wearable devices and VBT. As you will see researches about these topics are pretty recent, even the correlation between force and velocity was found by Hill in 1940. The lack of studies during all these years is due to the need of a proper technology; reliable, practical and economically sustainable, that modern Linear Positioning Transducers (LPT) are.

> LPT DEVICES RELIABILITY

The first LPT devices, and still the most used in sport performance, are typically made by a central processing unit that, through a retractable cable that is linked to the equipment, such a barbell, can measure the velocity of the lift and then the acceleration. They also stream real time feedbacks displaying valors on a screen.  Several studies have been conducted about measurements of errors and the reliability of LPT devices and all of them showed relative and absolute reliability to be acceptable. 1)Bosco C., Belli A., Astrua M., Tihanyi J., Pozzo R., Kellis S., Tsarpela O., Foti C., Manno R., Tranquilli C., ” A dynamometer for evaluation of dynamic muscle work”. European Journal of Applied Physiology. 2)Cronin J.B., Hing R.D., McNair P.J., “Reliability and validity of a linear position transducer for measuring jump performance”. Journal of Strength and Conditioning Research.

Unlike these kind of LPT devices, Beast is wireless and wearable. This means that it is attachable almost everywhere and allows a larger number of exercises. Furthermore it is lighter and easier to transport in outdoor training sessions, or when you are traveling with teams in summer camps or games.

> VELOCITY BASED TRAINING METHOD

Without a strength tracker, it is almost impossible to implement VBT. In several articles of this blog we talked about the huge advantages of VBT method (read Velocity vs. Percentage Based Training article), but I want to underline some of the most important one more time:

1. Training with intention

One of the first things I learned using Beast is to perform every lift with the maximal possible speed and acceleration in the concentric phase. It has been shown that intended movements lead to larger strength improvement, velocity-specific response and higher rate of force development, compared with slow lifts.3) Behm D.G., Sale D.G. “Intended rather than actual movement velocity determines velocity-specific training response”. Journal of Applied Physiology. 4)Gonzalez-Badillo J.J., Sanchez-Medina L. “Movement velocity as a measure of loading intensity in resistance training”. International Journal of Sport Medicine.

2. Predicting load from velocity data

A very close relationship was found between Relative Load and the Mean Propulsive Velocity. It makes possible to determine with great precision which percentage of 1RM is being used as soon as the first rep of a set is performed with maximal voluntary velocity. 5)Gonzalez-Badillo J.J., Sanchez-Medina L. “Movement velocity as a measure of loading intensity in resistance training”. International Journal of Sport Medicine.

3. Autoregulation

As known, 1RM is subjected of daily variation. This fact can make linear periodization, with the predetermination of the training loads in advance, less effective. In fact, it has been demonstrated that Daily Undulating Periodization can lead to greater improvements in 1RM bench press strength and squat strength over a 6 week training period and in the number of repetition performed at a weight of 225lb in the bench press. 6)J.B. Mann, J.P. Thyfault, P.A. Ivey, S.P. Sayers “The effect of autoregulatory progressive resistance exercise vs. Linear Periodization on strength improvement in college athletes”. Journal of Strength and conditioning research.

By this point of view, Velocity Loss is an objective and reliable indicator of the level of metabolic stress and fatigue of an athlete 7)(Gonzalez-Badillo J.J., Sanchez-Medina L. “Velocity Loss as an indicator of neuromuscular fatigue during resistance training” Medicine and Science in Sports and Exercises.) , so it permits a less rough autoregulation than other subjective methods.

> REAL TIME PERFORMANCE FEEDBACK

The feature of displaying the results of the current performance in real time is very motivating for the athlete and adds a lot information about the task he has to accomplish. Feedback and the knowledge of the results has shown to have a great influence on the performance, especially when fatigue sets in, and it also create competition between athletes in the training environment. 8)A. Randell, J. Cronin, J. Keogh, N. Gill, M. Pedersen “Effect of performance feedback during 6 weeks of velocity based squat jump training” Journal of Strength and Conditioning Research. 9)R.M. Sousa Mendes, M.A. Bandeira Godinho “Knowledge of results precision and learning: a review” Revista de Psicologia del Deporte

> NOT ONLY VELOCITY

Power is the result of strength and velocity and its value is fundamental in every sport performance. It is known that maximum power generated by an athlete occurs in highly variable 1RM percentage intervals, which may range from 30 to 80% of the 1RM, depending on training level.  But in most of the studies, 1RM percentage is considered a measure of intensity rather than an indicator of power produced. To determinate the exact value of the power reached by an athlete you need an accelerometer. A study on the effect of a Maximal Power Training Cycle of High Level 400m Hurdlers showed improvements in 1RM and in their Maximum Power. Furthermore, they showed that athletes were able to generate more power with each absolute load, thus modifying the force-velocity relationship and having a positive impact on the rate of force development. This requires the specific load that produces maximum power in each athlete to be determined. 10)C. Balsalobre-Fernandez, C.M. Tejero-Gonzalez, J. Del Campo-Vecino, D. Alonso-Curiel. “The effects of a Maximal Power Training Cycle on the Strength, Maximum Power, Vertical Jump Height and Acceleration of High Level 400meter Hurdlers” Journal of Human Kinetics volume. 

After this general review of the most important effects and benefits of using wearable strength trackers and VBT method, this following chart is a resume for the lovers of numbers:

TOPIC OF THE STUDYRESULTSREFERENCE
LPT RELIABILITY: validation of a dynamometer for evaluation of dynamic muscle work. Subjects were asked to perform half squat exercises. Maximal error due to the measurements system was calculated to be less than 0,3% for Average Push-Off Force, 0,9% for Average Push-off Velocity and 1,2% for Average Push-off Power.Bosco C., Belli A., Astrua M., Tihanyi J., Pozzo R., Kellis S., Tsarpela O., Foti C., Manno R., Tranquilli C., " A dynamometer for evaluation of dynamic muscle work". European Journal of Applied Physiology.
LPT RELIABILITY: detailed reliability data for LPTs in isolation.They reported good reliability for force-related variables during a countermovement jump, with coefficient of variation values ranging between 2,1 and 7,4%.Cronin J.B., Hing R.D., McNair P.J., "Reliability and validity of a linear position transducer for measuring jump performance". Journal of Strength and Conditioning Research
EFFECTS OF INTENDED MOVEMENTS: a comparison between fast and low movement effects.High-velocity movements increased most the peak torque, in comparison to lower velocities (38%).Behm D.G., Sale D.G. "Intended rather than actual movement velocity determines velocity-specific training response". Journal of Applied Physiology.
EFFECTS OF INTENDED MOVEMENTS: influence of the velocity atteined with 1RM and its stability after modifying the 1RM.Relationship between Mean Propulsive Velocity and Load (%1RM) was observed (R2=0,98). Mean Velocity attained with 1RM was 0,4m/s-1 +/- 0,16 and was found to influence the MPV attained with each %1RM. Despite a mean increase of 9,3% in 1RM from T1 to T2, MPV for %1RM remained stable.Gonzalez-Badillo J.J., Sanchez-Medina L. "Movement velocity as a measure of loading intensity in resistance training". International Journal of Sport Medicine.
PREDICT LOAD FROM VELOCITY DATAIt has been observed differences between each 5% increment in relative load (from 30-100% 1RM) vary between 0,07 and 0.09 m/s-1.Gonzalez-Badillo J.J., Sanchez-Medina L. "Movement velocity as a measure of loading intensity in resistance training". International Journal of Sport Medicine
AUTOREGULATION: Comparison between APRE and LP methods. Autoregulatory progressive resistance ecxercise demonstrated greater improvements in 1RM bench press and squat strength, and in the number of repetition performed at a weight of 225 lb.J.B. Mann, J.P. Thyfault, P.A. Ivey, S.P. Sayers "The effect of autoregulatory progressive resistance exercise vs. Linear Periodization on strength improvement in college athletes". Journal of Strength and Conditioning Research
EFFECTS OF REAL TIME PERFORMANCE FEEDBACK The use of feedback during squat jump training was reported to be possibly (45-65%) beneficial to increasing vertical jump, 10m and 20m sprint performance, likely (83%) to be beneficial to increasing horizontal jump performance and almost certainly (99%) beneficial to increasing 30m performance.A. Randell, J. Cronin, J. Keogh, N. Gill, M. Pedersen "Effect of performance feedback during 6 weeks of velocity based squat jump training" Journal of Strength and Conditioning Research.
EFFECTS OF KNOWING THE EXACT MAXIMUM POWER TRAINING LOADThe results indicated the following statistically significant improvements: a 7,9% increase in RM, a 2,3% improvement in Squat Jump, a 1,43 decrease in the 30m sprint. a change in the RM percentage from 56 to 62%, a 11% relative percentage change for the percentage of 1RM at which maximum power was generated.

 

 

 

 

 

References   [ + ]

1. Bosco C., Belli A., Astrua M., Tihanyi J., Pozzo R., Kellis S., Tsarpela O., Foti C., Manno R., Tranquilli C., ” A dynamometer for evaluation of dynamic muscle work”. European Journal of Applied Physiology.
2. Cronin J.B., Hing R.D., McNair P.J., “Reliability and validity of a linear position transducer for measuring jump performance”. Journal of Strength and Conditioning Research.
3. Behm D.G., Sale D.G. “Intended rather than actual movement velocity determines velocity-specific training response”. Journal of Applied Physiology
4, 5. Gonzalez-Badillo J.J., Sanchez-Medina L. “Movement velocity as a measure of loading intensity in resistance training”. International Journal of Sport Medicine.
6. J.B. Mann, J.P. Thyfault, P.A. Ivey, S.P. Sayers “The effect of autoregulatory progressive resistance exercise vs. Linear Periodization on strength improvement in college athletes”. Journal of Strength and conditioning research.
7. (Gonzalez-Badillo J.J., Sanchez-Medina L. “Velocity Loss as an indicator of neuromuscular fatigue during resistance training” Medicine and Science in Sports and Exercises.) 
8. A. Randell, J. Cronin, J. Keogh, N. Gill, M. Pedersen “Effect of performance feedback during 6 weeks of velocity based squat jump training” Journal of Strength and Conditioning Research.
9. R.M. Sousa Mendes, M.A. Bandeira Godinho “Knowledge of results precision and learning: a review” Revista de Psicologia del Deporte
10. C. Balsalobre-Fernandez, C.M. Tejero-Gonzalez, J. Del Campo-Vecino, D. Alonso-Curiel. “The effects of a Maximal Power Training Cycle on the Strength, Maximum Power, Vertical Jump Height and Acceleration of High Level 400meter Hurdlers” Journal of Human Kinetics volume. 
Martina Marson

by Martina Marson

From kick boxing to free style wrestling, through functional and strength training. Beast Sensor addicted. Training is my job, my passion and my life.