Tuesday, November 11, 2014

Exercise Research Update Nov. '14 (2/2): Vibration Training for Athletes, Caffeine Muscle Size & Power, Time to Psyche Up, Myostatin Resp. to Strength & Comb. Training & More

Vibration training is for lazy men & women, only - right? It cannot speed up the adaptation process in athletes, right? And it certainly has no effects on body composition, right? Not exactly, scroll down and find out why.
For those of you who haven't read yesterday's first installment of this research update, I highly suggest you head over now, or after you've read today's follow up on additional vibration training for athletes, caffeine and the effect of muscle size on the strength boosting effects of caffeine, the benefits of and perfect time to psyche up before a sprint event and the muscular myoastatin response to strength, interval and combined training, to make sure you don't miss half this research update.

And if you are not interested in any of these news you may still appreciate the bottom line with a brief review of the latest evidence for the differential or identical effects of strength and hypertrophy training on the acute biochemical and neuromuscular responses justify the classification of strength- and hypertrophy-type resistance exercise.
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  • Additional vibration training valid for athletes to develop both strength and hypertrophy of the lower limbs, study shows. The researchers randomly assigned forty-one (32 men and 9 women) recreationally active subjects (21.4 ± 3.0 years old; 172.6 ± 10.9 cm; 70.9 ± 12.3 kg) to either two (G2) or three (G3) vibration training sessions per week for six weeks and measured the changes in maximum isokinetic strength, body composition, and performance in vertical jumps from the beginning to the end of the training cycle (Martinez-Pardo. 2014).

    The vibration training stimulus consisted of uniform vertical oscillations. holding an isometric quarter squat position with the feet shoulder-width apart - no fancy exercises or headstands on the plate ;-) After the familiarization week, subjects trained 2 or 3 days per week for 6 weeks (with the exception of the C G) using a vibrating incremental training program that began with 8 sets per session and increasing by 1 set weekly.

    Figure 1: Change in body composition over the course of the 6-week study period (Martinez-Pardo. 2014)
    The frequency of vibration (50 Hz), amplitude (4 mm), time of work (60 seconds), and time of rest (60 seconds) were constant for G2 and G3 groups, the increases in lean mass were not: While the G2 group gained "only" 0.9 ± 1.0 kg, while the subjects in the G3 group who participated  in three weekly vibration training sessions had a whopping 1.5 ± 0.7 kg more lean mass after only 3 sessions per week x 6 weeks = 16 sessions on the vibration plate.

    As it was to be expected, neither the total fat mass, nor the fat percentage (measured reliably by DEXA) changed statistically significantly and the bone mineral content, and bone mineral density of the men and women in both groups didn't change at all (previous studies show that vibration training can increase bone density or at least reduce the bone loss in people who are at risk of osteoporosis | de Zepetnek. 2009). 
  • Caffeine & muscle power - Larger muscle groups benefit more, study shows. Right from the labs of the University of Edinburgh comes the news that 6 mg/kg caffeine (CAF) increase the isokinetic peak torque of the knee extensors, ankle plantar flexors, elbow flexors and wrist flexors proportionally to the respective size of the muscle group.
    Figure 2: Relative increase in isokinetic peak torque values of the 4 muscle groups for the CAF vs. placebo treatments at an angular velocity of 60°/s (Timmins. 2014)
    More specifically, statistical analyses revealed a significant increase in isokinetic peak torque from PLA to CAF (p = 0.011) for all, but significant difference in isokinetic peak torque between muscle groups (p < 0.001).

    As the scientists point out, "[t]his research may be useful for competitive and recreational athletes aiming to increase strength-power performance," because they now know that (a) caffeine works and (b) that it will work better for larger vs. smaller muscle groups.
  • Figure 3: Mean change in performance for each condition and time interval. A) Overall 30-m sprint time. B) Acceleration phase of the sprint, i.e. 0- to 10-m lap time (Hammoudi-Nassib. 2014)
    Is it time to "psyche up", already? Scientists investigate relationship between time interval between psyching up and sprint performance. In their latest study researchers from the Tunisian Research Laboratory Sports Performance Optimization National Center of Medicine and Science in Sports (CNMSS) found that imagery techniques were specifically effective in enhancing the performance on the phase of acceleration (0–10 m) and on the overall sprint (0–30 m) when they were used immediately before performance and at 1- and 2-minute intervals.

    When the subjects were asked to use the same technique 3- and 5-minutes before the sprints, though, no effect was observed. As the researchers point out, their "findings support the hypothesis that the potential effect of the PU [psyching up] strategy on performance vanishes over time." (Hammoudi-Nassib. 2014)
  • Skeletal muscle myostatin response is identical for strength training (ST), interval training (IT) and concurrent training (CT), study finds. Researchers from the University of São Paulo tested the differential effects of the previously mentioned training regimen in thirty-seven physically active men over the course of an 8-week training period and found that ...
    • Figure 3: No sign. difference in myostatin response to training (de Souza. 2014)
      Type IIa and type I muscle fiber CSA increased from pre- to posttest only in the ST group (17.08 and 17.9%, respectively). 
    • The SMAD-7 gene expression significantly increased at the posttest in the ST (53.9%) and CT groups (39.3%). 
    • The MSTN and its regulatory genes ActIIb, FLST-3, FOXO-3a, and GASP-1 mRNA levels remained unchanged across time and groups. 
    Moroever, the one repetition maximum increased from pre- to posttest in both the ST and CT groups to a similar extent (ST = 18.5%; CT = 17.6%).

    In spite of the fact that the scientist say that their "findings are suggestive that MSTN and their regulatory genes at transcript level cannot differentiate muscle fiber CSA responses between CT and ST regimens in humans" (de Souza), one could still speculate that the non-significantly lower myostatin levels in the ST-only group (see Figure 3) may already have been enough to cause the small, but significant difference in typeIIa and type I fiber CSA increase from pre- to postttest the researchers observed.
Photo from FighterDiet.com -- Powerlifting training can yield similar results as classic hypertrophy training. Is this because the acute biochemical and neuromuscular responses do not differ | learn more 
Before I call it a day, I would still like to draw your attention to yet another study that was published in the latest issue of the Journal of Strength and Conditioning Research, one that tried to answer the question, whether "the acute biochemical and neuromuscular responses justify the classification of strength- and hypertrophy-type resistance exercise" (Nicholson. 2014) and found that the only difference between strength and hypertrophy type workouts - despite their significant different intensities, volumes, and rest times (STR: 4 × 6 repetitions, 85% 1 repetition maximum [1RM], 5-minute rest periods vs. HYP: 4 × 10 repetitions, 70% 1RM, 90-second rest periods) - was observable in the acid-base response to the workout. Accordingly, Nicholson et al. conclude that "practitioners to look beyond the classification of RE workouts when aiming to elicit specific physiological responses" (Nicholson. 2014). Maybe that's also why powerlifting- and hypertrophy-like workouts have been shown to yield very similar outcomes in recent studies (learn more)?
References:
  • de Souza et al. "Effects of Concurrent Strength and Endurance Training on Genes Related to Myostatin Signaling Pathway and Muscle Fiber Responses." Journal of Strength and Conditioning Research 28.11 (2014): 3215–3223.
  • de Zepetnek, JO Totosy, Lora M. Giangregorio, and B. Catharine Craven. "Whole-body vibration as potential intervention for people with low bone mineral density and osteoporosis: a review." J Rehabil Res Dev 46.4 (2009): 529-542.
  • Hammoudi-Nassib et al. "Time Interval Moderates the Relationship Between Psyching-up and Actual Sprint Performance." Journal of Strength and Conditioning Research 28.11 (2014): 3245–3254.
  • Martinez-Pardo et al. "Effect of a Whole-Body Vibration Training Modifying the Training Frequency of Workouts per Week in Active Adults." Journal of Strength & Conditioning 28.11 (2014):3255–3263.
  • Nicholson, et al. "Do the Acute Biochemical and Neuromuscular Responses Justify the Classification of Strength- and Hypertrophy-Type Resistance Exercise?"  Journal of Strength & Conditioning 28.11 (2014): 3188–3199.
  • Timmins & Saunders. "Effect of Caffeine Ingestion on Maximal Voluntary Contraction Strength in Upper- and Lower-Body Muscle Groups." Journal of Strength & Conditioning 28.11 (2014):3239–3244