Supplementation with an NR beetroot extract-based supplement provided neuromuscular advantages during metabolically taxing resistance exercise.

Chronic increases in testosterone levels can significantly increase hypertrophy and strength, as has been demonstrated by pharmacological intervention. However, decreases in basal testosterone levels can have the opposite result, as has been seen in hypogonadal populations. Because of these profound effects on hypertrophy and strength, testosterone has often been studied in conjunction with resistance exercise to examine whether the endocrine system plays a role in adaptations to the stimulus. Whereas some studies have demonstrated a chronic increase in basal testosterone, others have failed to find an adaptation to regular resistance exercise. However, improvements in strength and hypertrophy appear to be possible regardless of the presence of this adaptation. Testosterone has also been shown to acutely rise immediately following an acute resistance exercise bout. While this substantial mobilization of testosterone is brief, its effects are seen for several hours through the upregulation of the androgen receptor. The role of this acute response at present is unknown, but further study of the non-genomic action and possible intracrinological processes is warranted. This response does not seem to be necessary for resistance training adaptations to occur either, but whether this response optimizes such adaptations has not yet been determined.

It well-known that mental training improves skill performance. Here, we evaluated skill acquisition and consolidation after physical or motor imagery practice, by means of an arm pointing task requiring speed-accuracy trade-off. In the main experiment, we showed a significant enhancement of skill after both practices (72 training trials), with a better acquisition after physical practice. Interestingly, we found a positive impact of the passage of time (+ 6 h post training) on skill consolidation for the motor imagery training only, without any effect of sleep (+ 24 h post training) for none of the interventions. In a control experiment, we matched the gain in skill learning after physical training (new group) with that obtained after motor imagery training (main experiment) to evaluate skill consolidation after the same amount of learning. Skill performance in this control group deteriorated with the passage of time and sleep. In another control experiment, we increased the number of imagined trials (n = 100, new group) to compare the acquisition and consolidation processes of this group with that observed in the motor imagery group of the main experiment. We did not find significant differences between the two groups. These findings suggest that physical and motor imagery practice drive skill learning through different acquisition and consolidation processes.