Low energy availability and its implications for athletes
The interplay between nutrition and exercise has become a focal point of discussion for both sports enthusiasts and professionals. As the debate around low energy availability heats up, questions arise about its impact on muscle development and performance. Simultaneously, the choice between exercising in a fasted or fed state emerges as a contentious topic, with each presenting unique metabolic advantages. With the balance of benefits from pre-exercise feeding on one hand, and the intriguing metabolic outcomes of fasted exercise on the other, a thorough dive into the literature is essential.
A recent study led by Oxfeldt et al. (2023; PMID: 37329147) dove into an area that has long intrigued the sports science community: how does low energy availability affect muscle protein synthesis in trained athletes?
Defined as a state where energy intake doesn’t meet the demands of both exercise energy expenditure and basal physiological functions, low energy availability has been associated with a myriad of physiological consequences. But what does it mean for the athletic performance?
The results were enlightening. After examining thirty females over a ten-day period, the researchers found that low energy availability reduced both myofibrillar and sarcoplasmic muscle protein synthesis. Accompanying this was a decline in lean mass, urinary nitrogen balance, and even disruptions in certain hormone concentrations. The takeaway? Females aiming to gain muscle from their training routines should be cautious of low energy availability. It could be a potential stumbling block. Not only that, but it might also lead to negative consequences for skeletal muscle adaptations.
Another recent study (PMID: 37068775) delved into a specific period of dietary limitations: Ramadan. The study investigated the effects of resistance training timing during Ramadan intermittent fasting on muscle strength and hypertrophy in healthy male adults. Two groups were studied: one that trained in the late afternoon while fasting and another in the evening post-fast. Both groups underwent similar resistance training sessions.
Results highlighted that while resistance training didn’t detrimentally impact muscle hypertrophy for either group, the evening post-fast group saw significant strength improvements in squats and deadlifts by the 29th day of Ramadan compared to baseline measurements. In contrast, the fasting group showed no such gains. The findings suggest post-fast training during Ramadan might offer superior strength benefits.
The exploration of the intricate balance between nutrition and exercise has been an ongoing journey, with every study revealing more layers of complexity. The two clinical trials discussed provide a fascinating look into the direct implications of low energy availability in trained females and the effects of resistance training during Ramadan intermittent fasting.
It’s important to highlight that these studies are in line with other reviews in the literature that conclude that endurance athletes should avoid high intensity training while fasting (PMID: 32021500).
However, other authors that have previously explored similar terrains, like for instance, a meta-analysis by Ashtary-Larky et al. (2021; PMID: 33984329) examining the effects of intermittent fasting combined with resistance training on body composition, underscored potential benefits of intermittent fasting combined with resistance training. They found that this combination could help reduce body mass and body fat when juxtaposed with non-intermittent fasting control diets, all while preserving fat-free mass.
Drawing parallels, a 2018 systematic review by Aird et al. delved deeper into the effects of nutrition on exercise metabolism and performance, examining fasted vs fed-state effects (PMID: 29315892). This review concluded that while pre-exercise feeding does indeed enhance prolonged aerobic exercise performance, fasted exercise might induce beneficial metabolic adaptations in peripheral tissues. Interestingly, the review discerns that both fasted and fed states during exercise may lead to distinct outcomes. This divergence in exercise metabolism and performance based on feeding states offers an avenue for further research and exploration.
Thus, bringing it full circle, whether it’s the nuances of energy availability, the specifics of training during fasting periods, or the broader implications of fasted versus fed states during exercise, it’s evident that dietary patterns and their timing play a pivotal role in athletic performance and metabolic responses. As the body of research grows, athletes and those invested in the sports science community can hope to harness this knowledge to optimize training regimens and achieve desired outcomes.
