Thursday, November 24, 2016

Sitting or Lying, Not Walking Ups CrossFit Performance and Inter-Set Recovery | Nitrate Shot Allows for "One More Rep" | Electric Brain Stimulation Turns You into Hulk & More

I have to admit: This is an awkward collection of studies, but this is what happens if you (cherry) pick and discuss only those of the papers in the latest issue of the Journal of Strength and Conditio-ning Research which I personally found interesting / most interesting.
Some of you have probably already been missing it. The short science round-ups with the latest scientific evidence from exercise and nutrition science all around the world.

Studies such as Mosher's nitrate supplementation study that shows significant increases in the maximal number of reps during strength training. Studies such as Ouelette's study that refutes the notion that walking on a treadmill in-between sets is beneficial for trainees who are working out in the strength-conditioning range (crossfitters). Studies such as Wilson's review of the usefulness of CHO supplements with an unambiguous result in favor of CHO supplements. And studies like Lattari's who tested the effects of transcranial direct current stimulation (tDCS) on trained individuals' strength.
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  • Ingestion of  “BEET It Sport” Nitrate Shot Containing 6.4 mMol or 400 mg of nitrate Improves Resistance Exercise Performance Compared to Blackcurrant Placebo (Mosher. 2016) -- In the corresponding RCT (no sponsorship or bias declared), twelve recreationally active (age, 21 ± 2 years, height, 177.2 ± 4.0 cm, weight, 82.49 ± 9.78 kg) resistance-trained men were assigned in a double-blinded fashion to a randomized cross-over framework where participants ingested either (A) 70 ml of “BEET It Sport” nitrate shot containing 6.4 millimoles (mmol−1·L−1) or 400 mg of nitrate or (B) a blackcurrant placebo drink for six days before their performance during a standardized bench press workout at an intensity of 60% of their established 1 repetition maximum (1RM), for 3 sets until failure with 2 minutes rest interval between sets was tested.
    Figure 1: Mean (±SD) number of bench press repetitions for each set and condition totals. (*) denotes a significant main effect for condition (p <= 0.05 | Mosher. 2016).
    The analysis of the number of total repetitions completed, the total weight lifted, local and general rate of perceived exertion (RPE), and blood lactate showed no differences for the latter parameters, but a significant difference in repetitions to failure (p ≤ 0.001) and total weight lifted (p ≤ 0.001).

    The authors are thus right to conclude that their study "demonstrates that nitrate supplementation has the potential to improve resistance training performance and work output compared with a placebo" (Mosher. 2016). The same is yet also true for the statement that "f]urther studies are necessary to investigate long-term use and possible adaptations to resistance training with longer periods of dosing with nitrate" - and I would add: we also need studies to find out why some, but not all previous studies appear to confirm these effects.
  • Inter-set rest should be full rest, study suggests - Walking may impair recovery (Ouelette. 2016) -- In contrast to previous research, a new study by Ouellette, et al. that compared the effects of seated, supine, and walking interset rest strategies on work rate found that male and female members of a CrossFit® community (male n = 5, female n = 10) who performed a strenuous training session designed to enhance work capacity (cardiovascular and + muscular endurance exercises) achieved higher work rates on when they were lying supine on the floor and/or sitting on a flat bench than when they walked on a treadmill (velocity 0.67 m/s).
    Figure 1: Work rate mean and SD by rest strategy are presented (Ouellette. 2016).
    The individual work rate of the subjects was calculated for each of the three training session by summing session joules of work and dividing by the time to complete the training session (joules of work per second).

    Low(er) Carb CrossFitters May be Missing Out | 11.1% vs. 4% Rep Increase With 6-8g/kg CHO in 12-Min Rohoi Test | more
    Data were also collected during the interset rest periods (heart rate [HR], respiratory rate [RR], and volume of oxygen consumed) and were used to explain why one rest strategy may positively impact work rate compared with another. Statistical analyses revealed significant differences (p ≤ 0.05) between the passive and active rest strategies, with the passive strategies allowing for improved work rate (supine = 62.77 ± 7.32, seated = 63.66 ± 8.37, and walking = 60.61 ± 6.42 average joules of work per second). A complete analysis of the data does also reveal that the passive strategies resulted in superior HR, RR, and oxygen consumption recovery.
  • Does Carbohydrate Intake During Endurance Running Improve Performance? A Critical Review Says: It can be (Wilson. 2016)! After all, 13 of the 17 studies comparing a carbohydrate beverage(s) with water or a placebo found a between-condition performance benefit with carbohydrate.
    Figure 1: Forest plot of standardized effects sizes and 95% confidence intervals for time trial studies comparing an equivalent volume of carbohydrate beverage(s) with placebo (Wilson. 2016)
    Unfortunately, both the heterogeneity in protocols as well as the fact that the available data comes almost exclusively from studies on fasted young men, makes generalizations, as well as inferences regarding women, adolescents, older runners, and those competing in fed conditions difficult.
    Figure 2: Forest plot of standardized effects sizes and 95% confidence intervals for time-to-exhaustion studies comparing an equivalent volume of carbohydrate beverage(s) with placebo (Wilson. 2016).
    If you are a fasted, young man, however, it appears to be certain that you will benefit. More specifically:
    • performance benefits are most likely to occur during events >2 hours, although several studies showed benefits for tasks lasting 90–120 minutes; 
    • consuming carbohydrate beverages above ad libitum levels increases gastrointestinal discomfort without improving performance; 
    • carbohydrate gels do not influence performance for events lasting 16–21 km; and 
    • multiple saccharides may benefit events >2 hours if intake is ≥1.3 g·min−1 
    Future studies will, as Patrick B. Wilson, the author of the review, points out, have to "address [the formerly hinted at] limitations to further elucidate the role of carbohydrate ingestion during endurance running (Wilson. 2016).
Effects of tDCS on fatigue (OMNI-RES) and effect sizes for the total number of repetitions and perceived exertion (Lattari. 2016). The use of the device you see in the upper-left of the figure did yet not work for everyone. The scientists' analysis of the inter-individual variability of responders vs. non-responders revealed that ~70% benefitted from the a-tDCS treatment.
If the above studies blew away your brain, you better run for cover now: Eduardo Lattari et al. (2016) have recently taken aim right at your brain, when they tested the effects of transcranial direct current stimulation (tDCS), a form of neurostimulation which uses constant, low current delivered to the brain area of interest via electrodes on the scalp, on the strength of recreationally trained subjects.

And guess what: The technology that was originally developed to help patients with brain injuries or psychiatric conditions like major depressive disorder did the trick. After 20 minutes of tDCS, increased the maximal volume and decreased the subjects' perceived exertion significantly - this worked yet only when the anode (positive | a-tDCS) outlet was connected to the subjects' brains. The cathode (negative outlet | c-tDCS) had the opposite ergolytic effect (see Figure on the right) | Comment!
  • Lattari, Eduardo, et al. "Can transcranial direct current stimulation improves the resistance strength and decreases the rating perceived scale in recreational weight-training experience?." Journal of strength and conditioning research/National Strength & Conditioning Association (2016).
  • Mosher, Scott, et al. "Ingestion of a nitric oxide enhancing supplement improves resistance exercise performance." Journal of strength and conditioning research/National Strength & Conditioning Association (2016).
  • Ouellette, Kristen A., et al. "Comparison of the effects of seated, supine and walking inter-set rest strategies upon work rate." Journal of strength and conditioning research/National Strength & Conditioning Association (2015).
  • Wilson, Patrick B. "Does carbohydrate intake during endurance running improve performance? A critical review." Journal of strength and conditioning research/National Strength & Conditioning Association (2016).