Friday, January 30, 2015

RT & Vibration or Plyometric Training for Runners? Can You Outtrain Colon Cancer and How Does it Work? Plus: What's the Verdict on Exercise to Prevent Metabolic Damage?

Make room for cardio & strength training in your workout routine. Both offer significant and scientifically proven health benefits, but neither cardio or strength the will prevent diet-induced obesity, when you eat everything in sight.
Time for another installment of the SuppVersity Short News on exercise science. This installment features the effects of strength training associated with whole body vibration training on running economy and vertical stiffness (Roschel. 2015), the acute effects of plyometric intervention on sprinting performance (Mackala. 2015), the anti-colon-cancer effects of aerobic training (Frajacomo. 2015) and, finally, the effects of exercise training and energy expenditure following weight loss (Hunter. 2015).

When we are already talking "metabolic damage", let's top that off with a brief reminder that hyperphagia = eating everything in sight, not a reduced energy expenditure is the most significant contributor to post-diet weight regain.
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  • Do strength and body vibration training improve running economy? To answer this question it's imperative that we understand what exactly "running economy" (RE) actually is. Among exercise researchers RE is defined as the energy cost to maintain a sub-maximal running velocity. Practically speaking, this means than an increase in running economy will make a 10k run easier to run, a marathon seem a few kilometers shorter, etc.

    Past research has shown that both resistance training (RT) and whole body vibration training added to RT (WBV + RT) can influence an athletes running economy. The question Roschel et al. wanted to answer now was: Is it conceivable that the combination of both would have even more pronounced beneficial effects on the running economy in 15 recreational runners.
    To this ends, the subjects were divided into RT or WBV + RT groups. The running economy, one of its main correlates, the vertical stiffness (VS), as well as the lower-limb maximum dynamic strength (1RM half-squat) were assessed before and after the 6-week training period.
    Figure 1: While the strength performance increased in response to both resistance training alone (RT) and whole body vibration + resistance training (WBV+RT - left figure), there were no beneficial effects on running performance (right figure | Roschel. 2015).
    As the data in Figure 1 goes to show you there was a main time effect for 1RM, but no other statistically significant difference was observed. Neither conventional RT nor RT performed on a WBV platform improved VS and RE in recreational long distance runners. And while the scientists argue that
    "[i]t is possible that movement velocity was rather low and utilization of stretch-shortening cycle might have been compromised, impairing any expected improvement in RE" (Roschel. 2015),
    the study at hand still puts a question mark behind the assumption that any form of resistance and/or vibration training regimen will have beneficial effects on the running economy of recreational runners.
  • Do plyometrics increase sprint performance?  In their latest study Mackala et al. (2015) examined the effect of a short high intensity plyometric program on the improvement of explosive power of lower extremities and sprint performance as well as changes in sprinting stride variability in male sprinters.

    Fourteen healthy males sprinters (mean +/- SD: age 18.07 +/- 0.73 years, body mass 73 +/-9.14 kg, height 180.57 +/- 8.16 cm and best 100 m 10.89 +/- 0.23) participated in the experiment. The experimental protocol included: vertical jumping - squat jump (SJ) and countermovement jump (CMJ) and horizontal jumps; standing long jump (SLJ) and standing triple jumps(STJ) to assess lower body power, maximal running velocity; a 20-m flying start sprint that evaluated variability of 10 running steps and 60 m starting block sprint.

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    The short-term plyometric training program significantly increased the explosive power of lower extremities, both vertical and horizontal jumping improvement. However, the vertical jumps increased much more than the horizontal. The 20 m improvements were derived from an increase of stride frequency from 4.31 to 4.39 Hz, due to a decrease of ground contact time from 138 to 133 ms. This did not translate into step length changes. Therefore, the significantly increased frequency of stride (1.8%), which is a specific expression of ground contact time reduction during support phase, resulted in an increase of speed.

    Overall, the scientists conclude that the "training volume of two weeks (with six sessions) using high intensities (between 180 and 250 jumps per session) plyometric exercises can be recommended as the short term strategy that will optimize one's probability of reaching strong improvements in explosive power and sprint velocity performance" (Mackala. 2015).
  • Can aerobic training prevent colon cancer? The corresponding epidemiological evidence has been there for years, the mechanism by which aerobic training prevents the development of colon cancer had not yet been fully elucidated, though. In their latest study researchers from the University of São Paulo did thus try to find out what exactly it is that makes "cardio" cancer-protective.

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    What the scientists found when they analyzed the inflammatory response to swimming exercise in rodents was a significant increase in the anti-inflammatory cytokine IL-10 which was associated with a 36% reduced occurrence of colon preneoplastic lesions in the carcinogen-exposed mice.

    It does therefore appear clear that "L-10 is a pivotal element for antipreneoplastic effects of aerobic training on the colon" (Frajacomo. 2015) - or put simply: If interleukin 10 (IL-10) is activated by endurance training, this will stop cancer in the tracks.
  • Does working out help prevent or precipitate reductions in energy expenditure after weight loss? According to the latest study from the University of Alabama at Birmingham, exercise training prevents a decrease in energy expenditure, including free living energy expenditure separate from the exercise training, following weight loss.

    The researchers analyzed data from 140 pre-menopausal women who underwent an average of 25 pound weight loss during an 800 kcal/day diet of furnished food. One group aerobically trained 3 times/wk (40 min/d), another resistance trained 3 times/wk (10 exercises/2 sets x10 repetitions) and the third group did not exercise. DXA was used to measure body composition, indirect calorimetry to measure resting (REE) and walking energy expenditure, and doubly labeled water to measure total energy expenditure (TEE). Aerobic energy expenditure (AEE), anaerobic energy expenditure during resistance training (ARTE), and non-training physical activity energy expenditure (NEAT) were calculated.
    Figure 2: Changes in energy expenditure pre vs. post weight loss (Hunter. 2015)
    What they found was that the EE, REE, and NEAT all decreased following weight loss for the no exercise group. In the two exercise groups only REE decreased significantly. Furthermore in the resistance training group the non-training physical activity energy expenditure increased significantly. This could be a result of an increase in muscle mass and the corresponding energy costs of using it during the subjects everyday activity and/or an overall increase in physical activity - the scientists believe it's the latter.

    Whatever the reason for the NEAT increase may be, the study at hand confirms that working out - in particularly doing resistance training - can help you to avoid the post-diet weight gain by preventing or at least ameliorating the reduction in energy expenditure some people call "metabolic damage". It cannot however prevent you from ruining your results by (a) returning to your pre-diet dietary habits and / or (b) giving in to your cravings.
Body composition changes in male participants of the Minne- sota experiment (severe dieting + refeeding | Dulloo. 2015).
That's it for today, now go training to make sure your colon stays cancer free and your dieting efforts remain unharmed by a reduction in energy expenditure....

Speaking of which: Only recently a group of Swiss researchers reviewed the effects of dieting on the body composition of previously lean or at least non-obese individuals and found that "dieting makes the lean fatter" (Dullo. 2015). As the data in Figure 3 goes to show you, the post-dieting increase in body fat is yet mostly a result of post-dieting binges (hyperphagia) and not of "metabolic damage" | Comment on Facebook.
  • Dulloo, A. G., et al. "How dieting makes the lean fatter: from a perspective of body composition autoregulation through adipostats and proteinstats awaiting discovery." Obesity Reviews 16.S1 (2015): 25-35.
  • Frajacomo FT, Kannen V, Deminice R, Geraldino TH, Pereira-da-Silva G, Uyemura SA, Jordão-Jr AA, Garcia SB. "Aerobic Training Activates Interleukin 10 for Colon Anticarcinogenic Effects." Med Sci Sports Exerc. 2015 Jan 26
  • Hunter GR, Fisher G, Neumeier WH, Carter SJ, Plaisance EP. Exercise Training and Energy Expenditure following Weight Loss. Med Sci Sports Exerc. 2015 Jan 20.
  • Mackala, Krzysztof; Fostiak, Marek. "Acute effects of plyometric intervention - performance improvement and related changes in sprinting gait variability." Journal of Strength & Conditioning Research: Post Acceptance: January 26, 2015.
  • Roschel, Hamilton; Barroso, Renato; Tricoli, Valmor; Batista, Mauro Alexandre Benites; Acquesta, Fernanda Michelone; Serrão, Júlio Cerca; Ugrinowitsch, Carlos. "Effects of strength training associated with whole body vibration training on running economy and vertical stiffness." Journal of Strength & Conditioning Research: Post Acceptance: January 26, 2015.