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B-29 Basic Science World Congress/Poster - Energy Balance and Expenditure: Physical Activity Wednesday, June 1, 2016, 1: 00 PM - 6: 00 PM Room: Exhibit Hall A/B

The Energy Cost of Cross Training at a Constant Power Varies with User Cadence

773 Board #89 June 1, 2

00 PM - 3

30 PM

Hofmann, Cory; Robarge, Ross; Bromberg, Rachel; Juris, Paul

Author Information
Medicine & Science in Sports & Exercise: May 2016 - Volume 48 - Issue 5S - p 211-212
doi: 10.1249/01.mss.0000485636.12918.48
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There exists an optimal cadence for cyclic activities that is most energetically efficient for a given power output. The metabolic costs are primarily associated with two factors: the cost of doing ‘internal work’ resulting in moving the limbs in a cyclic fashion, and the ‘external work’ done on the environment (e.g., a bicycle pedal) or the body’s center or mass (e.g., walking, running). Despite the prevalence of cross trainers in fitness settings, experiments investigating metabolic costs under varying cadences at a fixed mechanical power on these devices are scarce.

PURPOSE: To quantify the energy cost of using a cross trainer when the user varied cadence while the machine adjusted resistance to maintain a constant external power.

METHODS: Eighteen healthy subjects (11M, 7F; 35 ± 11 yr) attended one laboratory session during which they exercised on a cross trainer at a workload (150 ± 42 watts) eliciting approximately 75% of age-predicted maximum heart rate at a cadence of 130 steps/min, then worked at a faster and slower cadence in a counterbalanced order (110, 150 steps/min). Metabolic cost (kcal/min) was quantified via indirect calorimetry, and compared across conditions with a one-way repeated measures ANOVA (α = 0.05).

RESULTS: Our findings suggest that working at 150 steps/min elicited greater cost (13.24 kcal/min, P < 0.001) relative to 130 steps/min (12.19 kcal/min) and 110 steps/min (11.61 kcal/min).

CONCLUSIONS: Altering cadence, independent of altering the rate of external work done on the environment, can result in significant changes in metabolic demand while exercising on a cross trainer. These data suggest that the most energetically costly strategy involves increasing the cadence at which an exerciser works, suggesting that the role of performing internal work may be a limiting factor when exercising on a cross trainer at a sub-anaerobic threshold.

© 2016 American College of Sports Medicine