Lab 5: Effect of non-contractile mass on power output and energy expenditure

How is treadmill exercise influenced by body mass?

The heavier the person, the higher the work rate

What is the calculation for work rate on a treadmill?

Work rate = mvg x slope

where velocity is in m/s (/3.6 to get from km/h to m/s) and slope is a percentage as a decimal

Why is true work rate higher than the equation predicts?

The equation doesn’t account for horizontal forward speed

What are the implications of non-contractile mass on performance? (5)

• In weight-bearing or locomotive exercise, excess non-contractile mass reduces acceleration, jump height, sprint speed, and climbing ability

• More non-contractile mass increases the metabolic cost of exercise, reducing endurance performance and increasing fatigue rate

• More non-contractile mass decreases acceleration and cadence, reducing sprint performance

• More non-contractile mass increases the load on joints and bones, increasing injury risk

• More non-contractile mass reduces efficiency in bodyweight movements, e.g., pull ups, making them disproportionately harder

What are the implications of non-contractile mass on exercise prescription? (5)

• Training must consider the lower power-to-weight ratio of individuals with greater non-contractile mass

• Load selection must account for total mass to ensure exercise intensity is not too high

• Aerobic training may be emphasised to improve movement economy by increasing non-contractile mass loss

• Resistance training should prioritise lean mass retention so that performance is maintained and metabolic rate stays higher

• Low impact exercises could reduce injury risk for those with greater non-contractile mass