Muscle contraction force conforms to muscle oxygenation during constant-activation voluntary forearm exercise.

New Findings: What is the central question of this study? In electrically stimulated skeletal muscle, force production is downregulated when oxygen delivery is compromised and rapidly restored upon oxygen delivery restoration. Whether 'oxygen conforming' of force production occurs during voluntary muscle activation in humans and whether it is exercise intensity dependent remains unknown. What is the main finding and its importance? Here, we show in humans that force at a given voluntary muscle activation does conform to a decrease in oxygen delivery and recovers rapidly and completely with restoration of oxygen delivery.

Potential effect of beetroot juice supplementation on exercise economy in well-trained females.

This study examined if acute dietary nitrate supplementation (140 mL beetroot juice, BRJ) would reduce oxygen consumption (O) during cycling at power outputs of 50 and 70% maximal oxygen consumption in 14 well-trained female Canadian University Ringette League athletes. BRJ had no effect on O or heart rate but significantly reduced ratings of perceived exertion (RPE) at both intensities. Individually, 4 participants responded to BRJ supplementation with a ≥3% reduction in O at the higher power output.