Recommended Reading for Sports Performance and Sports Medicine Geeks Everywhere
Posted by Josh Stone, MA, ATC, NASM-CPT, CES, PES, FNS on January 23, 2013
Sharing a breakdown of what I have discovered and read this past month. There is a little something for everyone here. Although there is a lot out there, these four articles (2 sports medicine, 2 performance) are my favorites. All have something unique, progressive or surprising about them. Enjoy!
Sports Medicine:
Muscle Force Output and Electromyographic Activity in Squats with Various Unstable Surfaces, from the latest JSCR.
When progressing through rehabilitation programs the practitioner consistently battles the question of priority: improve strength and risk pain, set-back? Do we focus on balance and have slow progression to strength development? Can we super-set strength with balance? Can we go hard strength one day and light balance the next? Here’s a novel idea (sarcasm), let’s do both at once.
Saeterbakken and Finland measured muscle force output through on stable and unstable surfaces. The measurement was done through surface EMG, and, yes, I question reliability of surface EMG, but it is the best option out there. What the authors found was surprising and useful. Performing isometric exercise on an unstable surface (BOSU Ball) produced lower force output, but muscle in the trunk and lower limb was similar when compared to the stable surface.
Why is this important? We have a solution to the aforementioned dilemma. We can overload the muscle to stimulate strength gains, while avoiding the load. This allows practitioners to meet obtain strength gains while avoiding the risk of set-back associated with high loading.
Full reference: Saeterbakken, AH and Finland, MS. Muscle force output and electromyographic activity in squats with various unstable surfaces. J Strength Cond Res 27(1): 130–136, 2013
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Assessing Post-surgical ACL Postural Control using a Wii Board was an article I came across Sports Med Research BlogSpot.
At first I was tepid on this article figuring it was just another article showing how Wii can be used as a modality to improve balance control. I quickly jumped to the conclusion and began saying “people, it’s not the Wii board; it’s the task of balancing and stressing local and global neuromuscular control mechanisms to improve postural control.” To my surprise I was wrong.
The authors did something rather unique and plugged the Wii board in to a laptop and utilized a customized software program to assess postural control. The authors received high-quality data that may help clinicians objectively quantify postural control and neuromuscular inefficiency. Few assessments exist that provide objective, reliable data. I would love to see the authors do another study to examine the specificity and sensitivity of assessment.
Full reference: Howells BE, Clark RA, Ardern CL, Bryant AL, Feller JA, Whitehead TS, & Webster KE. Br J of Sports Med. Epub ahead of print Dec 25, 2012.
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Performance Training:
EFFECTS OF COMBINED CREATINE AND SODIUM BICARBONATE SUPPLEMENTATION ON REPEATED SPRINT PERFORMANCE IN TRAINED MEN, from the latest JSCR.
When working with athletes on maximal speed or speed endurance, human physiology is our biggest limiting factor. Training allows body adaptation and physiological changes to improve performance and curb fatigue, but physiology is physiology – it can only be altered so much. Thus, supplements exist to cheat human physiology.
First a quick exercise physiology review. When performing maximal exertion activity the phosphocreatine system kicks in. Our cells gobble up free floating phosphocreatine stores as our primary source of energy. This energy supply gives us a maximum of 10 seconds worth of energy. Quickly our body begins breaking down glycogen stores so our body as energy to keep producing movement. After 60-90 seconds though if our intensity is still too high we hit our lactate threshold – the period where lactic acid build exceeds the cells removal rate – causing increased cellular acidity. Acidity inhibits enzymatic function and if you recall on your exercise physiology class; enzymes are responsible for breakdown of substrates to energy. So, 2 physiological factors inhibiting performance; 1- depletion of phosphocreatine, and 2- increased acidity causing enzymatic inhibition.
This study examines the combined effects of creatine and sodium bicarbonate (to retard acidic effects) supplementation of sprint performance. To no surprise the authors found that the combination of these supplements increased peak / mean power and attenuated the decline in power. Alas, we found a way to cheat human physiology.
Full reference: Barber, JJ, McDermott, AY, McGaughey, KJ, Olmstead, JD, and Hagobian, TA. Effects of combined creatine and sodium bicarbonate supplementation on repeated sprint performance in trained men. J Strength Cond Res. 27(1): 252–258, 2013.
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EFFECTS OF PROPRIOCEPTIVE NEUROMUSCULAR FACILITATION STRETCHING AND STATIC STRETCHING ON MAXIMAL VOLUNTARY CONTRACTION, from the latest JSCR.
A study done a few years ago demonstrated static stretching reduced power output and performance. Since then, there has been a lot of debate and negative press on static stretching on maximal voluntary contraction (MVC). Suddenly performance experts are saying “Static stretching is the worst thing you can do.”
This is not true! First the performance declined occurred after 45 second static holds. When a stretch was held for 30 seconds or less – as recommended – there was no performance loss. This was supported by a systematic literature review done Kay and Blazevich, published in the Journal of Neurophysiology last year (Jan 2012). So, because of the debate this study examined effects of PNF and static stretching on MVC.
Guess what, the static stretch parameters were to perform static stretches for 5 repetitions of 45 seconds. This sets/time exceeds the recommended static stretching variables of 2 sets of 30 seconds. So can you guess the outcome? Yes, you guessed it, the authors concluded, that both PNF and static stretching reduced MVC. Although this is a good study, you must take the data for what it is. Static stretching does not reduce MVC or performance measures if the stretch variables are 2 sets of 20-30 second holds. So please, before you start knocking static stretching understand the data you are interpreting.
Full reference: Miyahara, Y,Naito, H, Ogura, Y, Katamoto, S, and Aoki, J. Effects of proprioceptive neuromuscular facilitation stretching and static stretching on maximal voluntary contraction. J Strength Cond Res. 27(1): 195–201, 2013.
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