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Beyond brawn: can protein supplementation fuel aerobic improvement?

It's well known that protein supplementation pairs well with resistance training, but can casein outperform carbs when paired with cardio?

Study under review: Protein supplementation elicits greater gains in maximal oxygen uptake capacity and stimulates lean mass accretion during prolonged endurance training: a double-blind randomized controlled trial.

Introduction

Maximal oxygen uptake (also known as VO2max)[1] is the highest rate at which oxygen can be transported and utilized by the body during intense exercise. Since VO2max is considered to be the single best criterion[2] of aerobic (or cardiorespiratory) fitness, and as aerobic fitness is independently associated with positive health outcomes[3] as shown in Figure 1, many athletes and recreationally-active people aim to improve their aerobic fitness by performing endurance exercise. Indeed, endurance exercise has been shown to be effective in improving[4] cardiorespiratory fitness, likely as a result of a number of adaptations[5] that improve the ability of the cardiorespiratory system (heart, lungs, and blood) to deliver oxygen to exercising muscles and the ability[6] of the muscles to utilize oxygen.


Together with endurance exercise, nutrition plays an important role in improving aerobic fitness. For example, it has been relatively well-established that carbohydrate ingestion[7] around the time of exercise, as well as a sufficient intake of dietary carbohydrates to maintain the body’s glycogen stores, are associated with improved endurance performance. Although most of the attention has been on carbohydrates for improving endurance performance, there has also been increasing interest in the role of protein for enhancing endurance training adaptations. Research[8] suggests that dietary protein may play a critical role in supporting recovery from endurance exercise.

Despite the fact that acute protein ingestion has shown benefits for endurance exercise recovery[9] and performance[10], data on the role of protein supplementation in relation to the adaptive response to chronic endurance exercise is generally lacking. To date, only a handful of small studies[11][12][13] with important methodological limitations have investigated the effects of protein supplementation on the adaptations to endurance exercise, with conflicting results. The study under review was the first preregistered double-blind randomized trial to investigate the effects of protein supplementation on changes in VO2max after 10 weeks of endurance training.

Maximal oxygen uptake (VO2max) is the highest rate at which oxygen can be transported and utilized by the body during intense exercise, and the single best marker of aerobic fitness. While most studies have focused on carbohydrate ingestion for improving endurance training performance, recent research suggests that dietary protein may play an important role in promoting endurance training adaptations. However, only a handful of small studies have examined the effects of protein supplementation on endurance training-induced adaptations and aerobic fitness with chronic aerobic exercise. The study under review aimed to add to the limited body of literature by examining the effects of protein supplementation on changes in VO2max with endurance training.

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Other Articles in Issue #59 (September 2019)