Monday, August 22, 2016

Inspiratory Muscle Training, HIIT or RT for Your Kids? Cold Water Immersion & Altitude Training - Who Benefits, When?

This is about as intense as it gets in PA sessions. What about HIIT and RT in schools?
With the ahead-of-print publication of articles for one of the future issues of the Journal of Strength and Conditioning, it is about time for another SuppVersity Exercise Research Update in the short news.

Today's installment revolves around five question: (a) Who benefits from acute cold-water immersion? (b) Which athletes benefit most from altitude training? (c) Is inspiratory muscle training actually ergogenic? And (d) will exercise in the cold impair your immune function?
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  • Acute Responses to Resistance and High Intensity Interval Training in Adolescents (Harris. 2016) - HIIT may no longer be in the news daily, but it is still appealing to athletes of all ages - including adolescents. Accordingly, a recent study took a closer look at the acute physiological responses to HIIT and compared it to resistance training (RT) sessions that were matched for time and required comparable effort, in a school setting.

    Seventeen early adolescents (12.9 +/- 0.3 y) performed both RT (2-5 repetitions perceived short of failure at the end of each set) and HIIT (90% of age predicted maximum heart rate), equated for total work set and recovery period durations comprising of 12 'sets' of 30 s work followed by 30 s recovery (total session time 12 min). Variables of interest included oxygen consumption, set and session heart rate (HR) and rate of perceived exertion (RPE), and change in salivary cortisol (SC), salivary alpha amylase (S[alpha]A), and blood lactate (BL) from pre- to post-session.
    Figure 1:  Acute rel. increase in VO2 and lactate levels after resistance training and HIIT (Harris. 2016)
    Analyses were conducted to determine responses within and between the two different protocols. For both RT and HIIT there were very large increases pre- to post-trial for SC and BL, and only BL increased greater in HIIT (9.1 +/- 2.6 mmol/L) than RT (6.8 +/- 3.3 mmol/L). Mean set HR for both RT (170 +/- 9.1 bpm) and HIIT (179 +/- 5.6 bpm) was at least 85% of HR maximum. VO2 over all 12 sets was greater for HIIT (33.8 +/- 5.21 mL/kg/min) than RT (24.9 +/- 3.23 mL/kg/min).

    Eventually, the study does therefore confirm that intermittent forays into high, but not supra-maximal intensity exercise is a potent physiological stimulus in adolescents. What I would like to highlight, though, is the fact that this isn't true only for HIIT, but also for resistance training which is still falsely regarded solely as strength and muscle builder.
  • Controlled Frequency Breathing Reduces Inspiratory Muscle Fatigue, but is Another Training Technique that does not translate into Real World Benefits (Brutch. 2016) - Controlled frequency breathing (CFB) is a common swim training modality involving holding one's breath for about 7 to 10 strokes before taking another breath.

    In their latest study, Burtch et al. sought to examine the effects of CFB training on reducing respiratory muscle fatigue. Competitive college swimmers were randomly divided into either the CFB group that breathed every 7 to 10 strokes, or a control group that breathed every 3-4 strokes. Twenty swimmers completed the study. The training intervention included 5-6 weeks (16 sessions) of 12x50-m repetitions with breathing 8-10 breaths per 50m (control group), or 2-3 breaths per 50-m (CFB group). Inspiratory muscle fatigue was defined as the decrease in maximal inspiratory mouth-pressure (MIP) between rest and 46s after a 200 yard free-style swimming race [115s (SD 7)]. Aerobic capacity, pulmonary diffusing capacity, and running economy were also measured pre and post-training.
    Figure 2: Mechanisms by which inspiratory muscle training improves performance (Brunell University)
    Pooled results demonstrated a 12% decrease in MIP at 46s post-race [-15 (SD 14) cm H2O, Effect size = -0.48, p < 0.01]. After four weeks of training, only the CFB group prevented a decline in MIP values pre to 46 s post-race [-2 (13) cm H2O, p > 0.05]. However, swimming performance, aerobic capacity, pulmonary diffusing capacity, and running economy did not improve (p > 0.05) post-training in either group.

    "In conclusion, CFB training appears to prevent inspiratory muscle fatigue yet no difference was found in performance outcomes," the authors write and forget to highlight that this is not the first study to show that many experimentally verified benefits on potential determinants of exercise performance (cf. Figure 2) leave the actual performance variables unchanged - or, at least not significantly improved (here: -0.1 +/- 1.5s in CFP vs. +1.8 +/- 4.6 in the control group - a tentative benefit).
  • Can cold water immersion enhance recovery in elite Olympic weightlifters? An individualized perspective (Schimpchen. 2016) - I hope you still remember that your goals determine whether you should or should not use cold water immersion, right? The thing about the impaired gains if you do it in a training phase...?

    Using Ice / Cold Water Immersion After Workouts Will Impair Muscle & Strength Gains and Vascular Adaptations | more
    That does not mean, though, that its acute beneficial effects were void. In fact, previous studies have show - albeit ambiguously - that cold water immersion following intensive training sessions can enhance recovery athletes. In a new study, Jan Schimpchen et al. did now test (a) whether this is also the case for elite Olympic weightlifters, and (b) whether the differences could be explained by each athlete's individual response pattern.

    The entire German male Olympic weightlifting national team participated in the study (n=7), ensuring collection of data from elite athletes only.

    Using a randomized cross-over design, the athletes went through two high intensity training microcycles consisting of five training sessions that were either followed by a cold water immersion or passive recovery. Barbell speed in a snatch pull movement, blood parameters as well as subjective ratings of general fatigue and recovery were assessed throughout the study.
    Table 1: Statistical analysis of all parameters. Overall P-value refers to the interaction of condition x time (Schimpchen. 2016) | Of particular interest: The column in red! Why? It tells you the ratio of "responders" to "non-responders" to those whose performance actually suffered; eg. VO2max 21/60/19 %.
    Physical performance at two snatch pull intensities (85% 1RM: -0.15% vs. -0.22%, P=0.94; 90% 1RM: -0.7% vs. +1.23%, P=0.25) did not differ significantly (condition x time). While questionnaires revealed a significant decline in ratings of overall recovery (P<0.001) and a significantly higher rating of overall stress (P=0.03) over time, no significant differences between conditions (P=0.14; P=0.98) could be revealed. Similarly, neither of the analyzed blood parameters changed significantly between conditions over time (CK: P=0.53; Urea: P=0.43; Cortisol: P=0.59; Testosterone: P=0.53; Testosterone:Cortisol ratio: P=0.69).

    "In general, CWI did not prove to be an effective tool to enhance recovery in elite Olympic weightlifters over a three day intensive training period," Schimpchen et al. conclude, but add: "However, even though the group was rather homogeneous with regard to performance, there were considerable inter-subject differences in their response to CWI. It appears that athletes are best advised on a case-by-case basis" (Schimpchen. 2016).
  • The maximal mechanical capabilities of leg extensors muscles to generate velocity and power improve at altitude (García-Ramos. 2016) - For long altitude training has been thought of (especially by non-athletes) as a PEDish (performance enhancing drug) performance enhancer. More recently, however, several studies have shown that the benefits may - as in so many other cases - be significantly overrated.

    In a recent study, scientists did now aim (a) to analyze the effect of an acute exposure to terrestrial altitude on the force-velocity relationship parameters (maximum force [F0)], maximum velocity [V0)], and maximum power [P0)]) during a loaded squat jump (SJ), and (b) to compare unloaded SJ and countermovement jump (CMJ) performance between sea level and altitude conditions. Seventeen international swimmers were tested at sea level (295 m asl) and 7 days later at terrestrial altitude (2320 m asl) during their first 24 hours of altitude exposure. The maximum values of force and velocity were recorded during a loaded SJ (25-100% of body weight) to determine F0, V0, and P0 parameters.
    Figure 3: Rel. (in %) and Effect Size ES for inter-group differences (Garcia-Ramos. 2016)
    As the authors point out, "[i]nconsequential differences between environmental conditions were found for F0 (P = 0.993, 0.02%)" (ibid.). However, V0 (P = 0.038, 7.6%) and P0 (P = 0.004, 6.8%) were higher at altitude. Peak values of force (SJ: P = 0.420, 1.19%; CMJ: P = 0.010, 3.6%), power (SJ: P = 0.028, 3.5%; CMJ: P = 0.005, 3.82%), and take-off velocity (SJ: P = 0.071, 1.6%; CMJ: P = 0.009, 1.9%) recorded during the SJ and CMJ were also higher at altitude.

    "These results highlight the potential effect of an acute exposure to terrestrial altitude on enhancing vertical jump performance," the authors highlight and explain: "The increase in maximal power of the leg muscles at altitude is caused by an improvement in the theoretical maximal velocity at which lower limbs can extend with no significant changes for the theoretical maximal force" (Garcia-Ramos. 2016).
If someone markets his program the way Hof does, i.e. as a means to "Become A 'Super' Version Of Yourself In Just 10 Short, Life Transforming Weeks" (WimHof-Method.com), you should rightly be skeptical | Find out if it's a winner routine or just another transient fad.
Bottom line: That's it? Not exactly... there's still Lara Carlson et al.'s study that compared the salivary lymphocytes (s-LYMPH) response to aerobic training in cool vs. thermoneutral environments and found that "exercise in a cool environment produces smaller fluctuations in salivary immune cells as compared to resting levels" - a result that puts a question-mark behind the common assumption that exercise in the cold would increase your risk of infections.

Speaking of question-marks, you will find similar question marks after (a) the question whether cold-water immersion is good for you (not w/ every workout, because of impaired adaptation and not even acutely, because of individual differences), (b) which athletes benefit most from altitude training (with the latest study pointing away from the usual subjects, namely endurance athletes) and (c) the notion that every improvement in potential determinants of exercise performance will actually translate to practically and/or stat. significant performance increases | Comment!
References:
  • Brunell University. "Cardiovascular & Respiratory Physiology Research Group." College of Health and Life Sciences < http://www.brunel.ac.uk/chls/life-sciences/sport-health-and-exercise-sciences/research/csmhp/physiology > 
  • Burtch, et al. "Controlled Frequency Breathing Reduces Inspiratory Muscle Fatigue." Journal of Strength & Conditioning Research: Post Acceptance: August 16, 2016 - doi: 10.1519/JSC.0000000000001589
  • Carlson, L. "Salivary Lymphocyte Responses Follwing Acute Anaerobic Exercise In A Cool Environment." Journal of Strength & Conditioning Research: Post Acceptance: August 16, 2016 - doi: 10.1519/JSC.0000000000001593
  • García-Ramos, A. "The maximal mechanical capabilities of leg extensors muscles to generate velocity and power improve at altitude." Journal of Strength & Conditioning Research: Post Acceptance: August 16, 2016 - doi: 10.1519/JSC.0000000000001592
  • Harris, N. "Acute Responses To Resistance And High Intensity Interval Training In Adolescents." Journal of Strength & Conditioning Research: Post Acceptance: August 16, 2016 - doi: 10.1519/JSC.0000000000001590
  • Schimpchen, et al. "Can cold water immersion enhance recovery in elite Olympic weightlifters? An individualized perspective." Journal of Strength & Conditioning Research: Post Acceptance: August 16, 2016 - doi: 10.1519/JSC.0000000000001591