Concurrent brain endurance training improves endurance exercise performance.

Objectives: Mental fatigue impairs endurance exercise. Brain endurance training (BET) - engaging in cognitively fatiguing tasks during exercise - can develop resilience to mental fatigue and improve physical performance over physical training alone. The mechanism for this effect is unknown. This experiment examines if BET enhances performance over physical training and investigates potential underlying physiological mechanisms.

Design: A mixed design randomised control trial.

Methods: Pre- and post-testing: 36 participants completed dynamic rhythmic muscular endurance handgrip tasks requiring generation of as much force as possible once a second for 300s, performed under 3 counterbalanced conditions: following 600s of a 2-back memory/attention task (subsequent); while performing a 2-back task (concurrent); and on its own (solo). Cardiac activity, electromyographic forearm activity, pre-frontal cerebral haemodynamics (near infrared spectroscopy), and force were recorded. Training: Participants (randomised to a Control or BET group) completed 24 (6 weeks) submaximal hand contractions sessions. The BET group also completed concurrent cognitive tasks (2-back, Stroop). Measures of motivation, physical and mental exertion and mental fatigue were collected throughout.

Results: Endurance performance, across the 3 tasks, improved more following BET (32%) than Control (12%) (p<0.05). The better performance following BET occurred with a higher pre-frontal oxygenation during the post-training physical tasks over time relative to Control (p<0.05).

Conclusions: Concurrent BET improved endurance performance over physical training alone. This was accompanied by a training-induced maintenance of pre-frontal oxygenation, suggestive of reduced mental effort during physical activity.