1.
Is a vegan diet detrimental to endurance and muscle strength?
Boutros, GH, Landry-Duval, MA, Garzon, M, Karelis, AD
European journal of clinical nutrition. 2020;74(11):1550-1555
-
-
-
Plain language summary
There is a common belief amongst the general population that a vegan diet leads to lower exercise performance due to the potential lack of dietary protein and nutrients. However, previous research that compared aerobic capacity and muscle strength between different diet groups only showed marginal variance, if any at all. But it is criticized that these studies did not always distinguish between the multiple subtypes of vegetarian or veganism. Hence this study sought to focus specifically on the comparison of strict plant-based eaters with omnivores. The participants involved were 56 active women, around their mid-twenties, with an average Body Mass Index of 22. Assessed were estimated VO2 max (an indicator of aerobic fitness), submaximal endurance performance and upper and lower body muscle strength. The 3-day food diaries of each participant was analysed and showed a similar intake of energy and fats in both groups. Vegans had higher carbohydrate, fibre, vitamin C, iron, and magnesium consumption and lower intake of protein, leucine, alanine, saturated fat, vitamin D, and vitamin B12, when compared to omnivores. Whilst upper body strength appeared to be marginally lower in the vegan group, higher levels of estimated VO2 max and significantly higher submaximal endurance levels were observed. The results contradict the common belief, demonstrating that a vegan diet appears to have no detrimental impact on endurance and muscle strength in healthy, young and lean women. In fact, the findings suggest that a vegan diet can be advantageous on endurance performance compared to omnivores. The authors propose that the higher intake of carbohydrates amongst vegans could be linked to better endurance performance and that such a plant-based diet can have favourable effects on oxidative stress and inflammatory profiles. The outcomes of this study may be of interest to those supporting the sports performance of strict plant-based eaters.
Abstract
BACKGROUND/OBJECTIVES In the general population, there is a popular belief that a vegan diet may be associated with a lower exercise performance due to the lack of certain nutrients in vegan individuals. Thus, the purpose of the present study was to examine endurance and muscle strength differences between vegan and omnivore participants. SUBJECTS/METHODS We studied 56 healthy young lean physically active women (age: 25.6 ± 4.1 years; body mass index: 22 ± 1.9 kg/m2). Participants were classified as vegan (n = 28) or omnivore (n = 28) based on their eating habits. All volunteers followed either a vegan or an omnivore diet for at least 2 years. Anthropometric measurements, body composition, estimated maximal oxygen consumption (VO2 max), a submaximal endurance test (70% of VO2 max), muscle strength (leg and chest press), and dietary factors were measured. RESULTS Both groups were comparable for physical activity levels, body mass index, percent body fat, lean body mass, and muscle strength. However, vegans had a significantly higher estimated VO2 max (44.5 ± 5.2 vs. 41.6 ± 4.6 ml/kg/min; p = 0.03, respectively) and submaximal endurance time to exhaustion (12.2 ± 5.7 vs. 8.8 ± 3.0 min; p = 0.007, respectively) compared with omnivores. CONCLUSIONS The results suggest that a vegan diet does not seem to be detrimental to endurance and muscle strength in healthy young lean women. In fact, our study showed that submaximal endurance might be better in vegans compared with omnivores. Therefore, these findings contradict the popular belief of the general population.
2.
Time-restricted eating effects on performance, immune function, and body composition in elite cyclists: a randomized controlled trial.
Moro, T, Tinsley, G, Longo, G, Grigoletto, D, Bianco, A, Ferraris, C, Guglielmetti, M, Veneto, A, Tagliabue, A, Marcolin, G, et al
Journal of the International Society of Sports Nutrition. 2020;17(1):65
-
-
-
Free full text
Plain language summary
Adequate nutrition is important for elite athletes, as nutrient availability influences energy expenditure, body composition, performance and exercise-induced immune responses. Time-restricted eating (TRE) is a form of intermittent fasting that has received much interest in recent years. Previous research of TRE suggested beneficial effects on performance in untrained individuals, by allowing weight loss whilst maintaining muscle functions. These qualities are of interest for endurance cyclists hence the authors of this study sought to investigate the impact of TRE in elite cyclists. Sixteen under-23 year old, elite cyclists were randomly assigned to eat within a TRE window of 8-hr or 15hr window during a 4-week, high-level endurance training phase. Both groups consumed their full estimated energy needs and markers such as fat and fat-free mass, VO2 max, basal metabolism, blood counts, anabolic hormones and inflammatory markers were measured. As a result, TRE produced weight loss, improved body composition and increased peak power output in relation to body weight without compromising aerobic performance. Furthermore, the TRE pattern proved helpful in mitigating some of the exercise-induced suppressions of the immune system. The authors concluded that TRE could be considered as part of a performance nutrition plan in endurance athletes. Particularly where there is a need to reduce body fat mass or for the management of training-induced depression of the immune system and associated respiratory infection susceptibility. This can be of clinical relevance in the support of endurance athletes.
Abstract
BACKGROUND Although there is substantial interest in intermittent fasting as a dietary approach in active individuals, information regarding its effects in elite endurance athletes is currently unavailable. The present parallel randomized trial investigated the effects of a particular intermittent fasting approach, called time-restricted eating (TRE), during 4 weeks of high-level endurance training. METHODS Sixteen elite under-23 cyclists were randomly assigned either to a TRE group or a control group (ND). The TRE group consumed 100% of its estimated daily energy needs in an 8-h time window (from 10:00 a.m. to 6:00 p.m.) whilst energy intake in the ND group was distributed in 3 meals consumed between 7:00 a.m. and 9:00 p.m. Fat and fat-free mass were estimated by bioelectrical impedance analysis and VO2max and basal metabolism by indirect gas analyzer. In addition, blood counts, anabolic hormones (i.e. free testosterone, IGF-1) and inflammatory markers (i.e. IL-6, TNF-α) were assessed. RESULTS TRE reduced body weight (- 2%; p = 0.04) and fat mass percentage (- 1.1%; p = 0.01) with no change in fat-free mass. Performance tests showed no significant differences between groups, however the peak power output/body weight ratio (PPO/BW) improved in TRE group due to weight loss (p = 0.02). Free testosterone and IGF-1 decreased significantly (p = 0.01 and p = 0.03 respectively) in TRE group. Leucocyte count decreased in ND group (p = 0.02) whilst the neutrophils-to-lymphocytes ratio (NLR) decreased significantly (p = 0.03) in TRE group. CONCLUSIONS Our results suggest that a TRE program with an 8-h feeding window elicits weight loss, improves body composition and increases PPO/BW in elite cyclists. TRE could also be beneficial for reducing inflammation and may have a protective effect on some components of the immune system. Overall, TRE could be considered as a component of a periodized nutrition plan in endurance athletes. TRIAL REGISTRATION This trial was retrospectively registered at clinicaltrials.gov as NCT04320784 on 25 March 2020.