Tag: EliteForm

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Snippit 90 ► The Isometric Squat as a measure of strength and explosiveness

April 13, 2020 Snippit Sports Science Podcast

Happy Easter everyone.

Isometric training is very topical at the moment with the current situation that most of us are currently experiencing. Today’s episode follows on the first 3 in the series of Isometric training. In particular we look at the isometric squat and how it relates to measures of strength and explosiveness. After this episode we have another 2 isometric papers to round out this series.

doi: 10.1519/JSC.0000000000000751.

The use of the isometric squat as a measure of strength and explosiveness.

Bazyler CD¹, Beckham GK, Sato K.

J Strength Cond Res. 2015 May;29(5):1386-92.

Abstract

The isometric squat has been used to detect changes in kinetic variables as a result of training; however, controversy exists in its application to dynamic multijoint tasks. Thus, the purpose of this study was to further examine the relationship between isometric squat kinetic variables and isoinertial strength measures.

Subjects (17 men, 1-repetition maximum [1RM]: 148.2 ± 23.4 kg) performed squats 2 d · wk(-1) for 12 weeks and were tested on 1RM squat, 1RM partial squat, and isometric squat at 90° and 120° of knee flexion.

Test-retest reliability was very good for all isometric measures (intraclass correlation coefficients > 0.90); however, rate of force development 250 milliseconds at 90° and 120° seemed to have a higher systematic error (relative technical error of measurement = 8.12%, 9.44%).

Pearson product-moment correlations indicated strong relationships between isometric peak force at 90° (IPF 90°) and 1RM squat (r = 0.86), and IPF 120° and 1RM partial squat (r = 0.79). Impulse 250 milliseconds (IMP) at 90° and 120° exhibited moderate to strong correlations with 1RM squat (r = 0.70, 0.58) and partial squat (r = 0.73, 0.62), respectively.

Rate of force development at 90° and 120° exhibited weak to moderate correlations with 1RM squat (r = 0.55, 0.43) and partial squat (r = 0.32, 0.42), respectively.

These findings demonstrate a degree of joint angle specificity to dynamic tasks for rapid and peak isometric force production.

In conclusion, an isometric squat performed at 90° and 120° is a reliable testing measure that can provide a strong indication of changes in strength and explosiveness during training.

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Snippit 84 ► Passive heating and cooling – the effects on muscle activation and force production

January 27, 2020 Snippit Sports Science Podcast

Hi everyone,

Today’s podcast is our second last in this heat series. We hope you’ve enjoyed this small continuous series of the role of heat in muscle physiology and performance.

Passive hyperthermia reduces voluntary activation and isometric force production.

Morrison S¹, Sleivert GG, Cheung SS.

Eur J Appl Physiol. 2004 May;91(5-6):729-36. Epub 2004 Mar 11.

Abstract

It has been suggested that a critically high body core temperature may impair central neuromuscular activation and cause fatigue. We investigated the effects of passive hyperthermia on maximal isometric force production (MVC) and voluntary activation (VA) to determine the relative roles of skin (T(sk)) and body core temperature ( T(c)) on these factors.

Twenty-two males [VO(2max)=64.2 (8.9) ml x kg(-1) min(-1), body fat=8.2 (3.9)%] were seated in a knee-extension myograph, then passively heated from 37.4 to 39.4 degrees C rectal temperature (T(re)) and then cooled back to 37.4(o)C using a liquid conditioning garment.

Voluntary strength and VA (interpolated twitch) were examined during an isometric 10-s MVC at 0.5 degrees C intervals during both heating and cooling.

Passive heating to a T(c) of 39.4(o)C reduced VA by 11 (11)% and MVC by 13 (18)% (P<0.05), but rapid skin cooling, with a concomitant reduction in cardiovascular strain [percentage heart rate reserve decreased from 64 (11)% to 29 (11)%] and psychophysical strain did not restore either of these measures to baseline. Only when cooling lowered T(c) back to normal did VA and MVC return to baseline (P<0.05). We conclude that an elevated T(c) reduces VA during isometric MVC, and neither T(sk) nor cardiovascular or psychophysical strain modulates this response.

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Optimising protein consumption to maximise your strength gains.

October 21, 2019 Snippit Sports Science Podcast

Hi everyone,

Thanks for you continued support. Today’s article looks into the plethora of information that surround protein consumption for improved muscle building:

How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution

Journal of the International Society of Sports Nutrition volume 15, Article number: 10 (2018)

Abstract

Controversy exists about the maximum amount of protein that can be utilized for lean tissue-building purposes in a single meal for those involved in regimented resistance training. It has been proposed that muscle protein synthesis is maximized in young adults with an intake of ~ 20–25 g of a high-quality protein; anything above this amount is believed to be oxidized for energy or transaminated to form urea and other organic acids. However, these findings are specific to the provision of fast-digesting proteins without the addition of other macronutrients. Consumption of slower-acting protein sources, particularly when consumed in combination with other macronutrients, would delay absorption and thus conceivably enhance the utilization of the constituent amino acids. The purpose of this paper was twofold: 1) to objectively review the literature in an effort to determine an upper anabolic threshold for per-meal protein intake; 2) draw relevant conclusions based on the current data so as to elucidate guidelines for per-meal daily protein distribution to optimize lean tissue accretion. Both acute and long-term studies on the topic were evaluated and their findings placed into context with respect to per-meal utilization of protein and the associated implications to distribution of protein feedings across the course of a day. The preponderance of data indicate that while consumption of higher protein doses (> 20 g) results in greater AA oxidation, this is not the fate for all the additional ingested AAs as some are utilized for tissue-building purposes. Based on the current evidence, we conclude that to maximize anabolism one should consume protein at a target intake of 0.4 g/kg/meal across a minimum of four meals in order to reach a minimumof 1.6 g/kg/day. Using the upper daily intake of 2.2 g/kg/day reported in the literature spread out over the same four meals would necessitate a maximum of 0.55 g/kg/meal.

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Considerations for optimising BFR pressures during aerobic exercise

October 7, 2019 Snippit Sports Science Podcast

Hi there,

We are finally back – Jared and I have finally synced our schedules to do an episode together. We are trying some new software called SquadCast to try and improve the quality of the internet recording – I think the audio is much better on this episode.

We are quite busy at the moment so we have decided in the short term to push our podcast release to every 2 weeks. Jared in particular is in the back-end of his thesis writing so it is great he is able to take a little bit of his valuable time out to come onto the podcast.

As always we are grateful to our sponsor EliteForm who have integrated Velocity Based Training through the use of 3D camera system with an online Strength planner so please give them a visit at Eliteform.com (Also we forgot to acknowledge them in the introduction so hence our extra shout out here.)

Today’s episode from a practical standpoint helps to understand the optimisation of Blood Flow Restriction pressures when doing aerobic (stationary-based) exercise. I personally have found that dropping my pre-determined BFR pressure by around 20mmHg works best and that if I stayed at this pressure (I usually do my strength training at) it is just doesn’t feel right and is too high. The debate of BFR pressures is an ongoing on and this article helps shed some light as to some great evidence.

Effects of Different Percentages of Blood Flow Restriction on Energy Expenditure.

Pfeiffer PS¹, Cirilo-Sousa MS¹, Santos HHD².

Int J Sports Med. 2019 Mar;40(3):186-190. doi: 10.1055/a-0828-8295. Epub 2019 Jan 31.

Abstract

The study aimed to analyze the effect of different levels of blood flow restriction (BFR) on energy expenditure (EE) and subjective perceptions of discomfort (SPD) during aerobic exercises.

A sample group of 24 young men was required to walk on a treadmill for 14 min at 40% of their maximum speed, with 4 different percentages of BFR (0, 50, 80 and 100%) applied in the lower limbs (LL) once a week with a 7-day interval between the 4 evaluations. EE data were collected during the exercise periods; SPD data were collected after the exercises.

There was a significant increase in EE at 50, 80 and 100% BFR compared to the condition without BFR, and between 50 and 100% BFR; however, there were no differences between 50 and 80% and 80 and 100% BFR. Discomfort showed a significant increase according to the increase in BFR. During the walking exercises with BFR, the EE strongly increased until 50% of BFR; after this level the additional increases slowed.

It can be concluded that when performing aerobic exercises with BFR, there is no need to use BFR levels above 50% to reach satisfying level of EE with only a moderate level of discomfort to the practitioner.

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