Tuesday, February 10, 2015

Exercise Quickie: HIIT as 24h+ Muscle Builder for the Elderly | Caffeine Without Ergogenic Effects on Biceps Curls

Caffeine won't do the "last rep" for ya.
Time for a brief review of the latest exercise and supplementation science in the SuppVersity Short News. You can see an overview of all previous articles in an RSS feed here.

This time you can take a look at the surprisingly lasting pro-anabolic effects of HIIT as measured by skeletal muscle protein synthesis in the elderly and the similarly surprising finding that caffeine - even if it's consumed in significant doses before a workout - will not have you curl an extra pound on either barbell or dumbbell curls.
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  • 27% increase in protein synthesis even 24h after HIIT exercise in the elderly - Resistance exercise (RE) and aerobic exercise are recommended for older adults for fitness and strength. High-intensity interval exercise (HIIT) is an understudied but potent potential alternative to aerobic exercise. A recent study from the McMaster University aimed to determine how each mode of exercise affected the integrated day-to-day response of muscle protein synthesis.

    To do so, they recruited 22 sedentary men (mean age = 22; 67±4 years; body mass index: 27.0±2.6 kg m- 2 [mean ± SEM]) who were randomly assigned to perform resistance training, aerobic exercise, or HIIT. The participants consumed a stable isotope tracer (D2O) for 9 days. Daily saliva samples were taken to measure tracer incorporation in body water. Muscle biopsies were obtained on Days 5-8 of D2O consumption to measure tracer incorporation into muscle at rest, 24 hours, and 48 hours following each exercise bout: RE (3 × 10 repetitions: leg extensor and press, 95% 10RM), HIIT (10 × 1 minute, 95% maximal heart rate [HRmax]), or aerobic exercise (30 minutes, 55%-60% HRmax).
    Figure 1: Myofirillar (left) and sarcoplasmic (right) protein fractional synthesis rate (FSR) at baseline and postexercise. Data are means ± SEM. Bars bearing different letters are signifiantly different within each exercise group | AE = aerobic exercise; HIIT = high-intensity interval exercise; RE = resistance exercise (Bell. 2015).
    What the scientists found is quite surprising: While resistance training showed, as it was expected, the greatest increase in fractional protein synthesis immediately, post workout, only the HIIT protocol lead do significant increases in sarcoplasmic protein fractional synthetic rate 24-hour postexercise (2.30±0.34% d- 1 vs 1.83±0.21% d- 1).

    That does not mean that HIIT is the better muscle builder, though. Specifically in view of the fact that it's the myofibrilar, not the sarcoplasmic protein synthesis rate that bunks with aging (Balagopal. 1997), the higher myofibrilar post-workout protein synthesis after the relatively low volume resistance training session is more important than the long-lasting elevation of the protein influx into the sarcoplasma, a muscle protein fraction that is involved in the anaerobic ATP production, intracellular transport, and several other enzyme functions. 
  • Stronger biceps with caffeine? No, ... at least during insometric contractions the administration of 5 mg/kg and 10 mg/kg caffeine does not have ergogenic effects on the elbow flexors.
    That's at least what the latest study from the University of Kansas shows. In their 13 recreationally trained male subjects, the ingestion of the aforementioned amounts of caffeine in form of of a caffeineated drink did not lead to significant increases in any of the relevant performance markers.
    Figure 2: Caffeine did not have significant ergogenic effects; at least the rate of torque development did increase, though (Trevino. 2015).
    In contrast to previous research which has indicated that under certain conditions, caffeine may increase muscle force production during anaerobic activities (3,6,15,17). The results of our study revealed that caffeine did not significantly affect peak torque during the maximal isometric contractions. As Trevino et al. point out, this finding may result from a variety of factors:
    Figure 3: In contrast to the study at hand a study by Beck et al. found significant increases in bench press performance in slightly better trained subjects (Beck. 2006).
    "Past equivocal findings with caffeine ingestion and anaerobic performance may have resulted from the type of muscle action and exercise performed, caffeine dose used, muscle group tested, or training status of the subjects. Our protocol used a single-joint isometric exercise to test the effects of caffeine doses of 5 and 10 mg/kg of body mass on maximal strength of the elbow flexors in resistance trained males (participating in at least 2 training sessions per week). Beck et al. (2006) reported that a 201 mg dose of caffeine significantly increased bench press 1RM in resistance trained males (participating in at least 4 training sessions/week). 
    Because significant results were found with a caffeine dose less than ours (average absolute doses in the current study were 426.7 and 853.4 mg for the 0 and 5 mg/ kg body mass conditions, respectively), it seems that the exercise test and training status may have led to different findings between the studies" (Trevino. 2015).
    Next to the training status and the lack of familiarity with performing maximal muscle contrations (the subjects in Beck et al. (2006) trained 4 times per week, the ones in the study at hand only two times), the exercise may play a role as well. The bench press is after all a multi-joint exercise requiring dynamic involvement of the pectoralis major, deltoid, and triceps. The biceps curl, on the other hand is the classic single-joint exercise, where the CNS activating effect of caffeine may simply offer less benefits than on bench presses, squats and other multi-joint exercises. The same may be true for comparisons of large and small muscle groups and could explain why Astorino et al. (2010), Jacobson, et al. (1992) and Kalmar et al. (1999) found beneficial effect of caffeine on the leg extension performance of their subjects, while Trevino et al. were not able to detect ergogenic effects for the small elbow flexors.
The Latest on Caffeine, Exercise, Fat & Weight Loss - Increased Performance, Energy Expenditure (6%) & Fatty Acid Oxidation (27%) vs. Decreased Sleep Quality & Burnout | Learn how caffeine can benefit your exercise performance and energy expenditure and how much caffeine is too much caffeine in a recent SuppVersity article.
Bottom line: Let me make this clear. Neither of the two studies refutes any of the given truths of strength training and muscle building. The Bell study does in fact confirm that resistance training triggers the most pronounced increases in skeletal muscle protein synthesis - the fact that HIIT may have longer lasting overall effects, specifically in the sarcoplasmic protein fraction, is nice, but its practical relevance is highly questionable.

Similarly, the study by Trevino et al. which shows minimal, but non-significant beneficial effects of caffeine on the elbow flexors does not negate the many previously established beneficial effects of caffeine supplements on exercise performance. What it does, however, is to remind us that it is not possible to transfer the results obtained in one group of trainees on one particular muscle group 1:1 to another group of trainees and/or another muscle group | Comment on Facebook!
  • Astorino, Todd A., et al. "Effect of two doses of caffeine on muscular function during isokinetic exercise." Medicine and science in sports and exercise 42.12 (2010): 2205-2210.
  • Balagopal, P., et al. "Effects of aging on in vivo synthesis of skeletal muscle myosin heavy-chain and sarcoplasmic protein in humans." American Journal of Physiology-Endocrinology And Metabolism 273.4 (1997): E790-E800.
  • Beck, Travis W., et al. "The acute effects of a caffeine-containing supplement on strength, muscular endurance, and anaerobic capabilities." The Journal of Strength & Conditioning Research 20.3 (2006): 506-510.
  • Bell et al. "Day-to-Day Changes in Muscle Protein Synthesis in Recovery From Resistance, Aerobic, and High-Intensity Interval Exercise in Older Men." J Gerontol A Biol Sci Med Sci (2015). 
  • Jacobson, B. H., et al. "Effect of caffeine on maximal strength and power in √©lite male athletes." British journal of sports medicine 26.4 (1992): 276-280.
  • Kalmar, J. M., and E. Cafarelli. "Effects of caffeine on neuromuscular function." Journal of Applied Physiology 87.2 (1999): 801-808.
  • Trevino, Michael A., et al. "Acute Effects of Caffeine on Strength and Muscle Activation of the Elbow Flexors." The Journal of Strength & Conditioning Research 29.2 (2015): 513-520.