|Caffeine won't do the "last rep" for ya.|
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.
- 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).
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). 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).
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.
- 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 élite 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.