Validity of Stryd Running Power for Estimating Metabolic Demand During Incline Treadmill Running.

Metabolic power and oxygen uptake were significantly higher at 6% and 8% inclines compared to 0% incline when running at a fixed Stryd power target.

• Metabolic power at 6% incline was 1063 (191) W and at 8% was 1079 (219) W, both significantly higher than 0% incline (1037 [191] W; P < .05 for all comparisons).
• Oxygen uptake at 6% incline was 3.02 (0.53) L/min and at 8% was 3.05 (0.62) L/min, compared to 2.95 (0.53) L/min at 0% incline.
• Metabolic power and oxygen uptake at 2% and 4% inclines were not significantly different from 0% incline (P > .05).
• Ten trained runners (4 females, 28 [8] y, VO2max 55.9 [9.1] mL/kg/min) performed 5-minute running trials at each incline condition.

Mechanical efficiency was significantly lower at 6% and 8% inclines compared to 0% incline.

• Mechanical efficiency at 6% incline was 21.6% (1.4%), significantly lower than 0% incline 22.1% (1.3%); P = .024.
• Mechanical efficiency at 8% incline was 21.3% (1.3%), significantly lower than 0% incline; P = .006.
• Mechanical efficiency at 2% and 4% inclines was not significantly different from 0% incline (P > .05).
• Stryd was estimated to underestimate metabolic power by approximately 2%–4% at steeper inclines.

Ventilation, breathing frequency, heart rate, and rating of perceived exertion did not differ significantly across incline conditions when running at a fixed Stryd power.

• Ventilation was not different across inclines (P = .550).
• Breathing frequency was not different across inclines (P = .273).
• Heart rate was not different across inclines (P = .924).
• Rating of perceived exertion was not different across inclines (P = .709).

The study used a Step-Ramp-Step exercise test to individually calibrate running intensity targets based on the respiratory compensation point.

• Participants performed a Step-Ramp-Step exercise test on a separate visit to estimate the running power at the respiratory compensation point.
• Treadmill speed was adjusted at each incline condition to elicit a running power 10% below the respiratory compensation point.
• Incline conditions of 0%, 2%, 4%, 6%, and 8% were performed in a random order.
• Metabolic power and mechanical efficiency were calculated from the final minute of each 5-minute trial.

Stryd running power is a useful metric to guide training during incline treadmill running despite slight underestimation of metabolic power at steeper grades.

• Stryd slightly underestimated metabolic power by approximately 2%–4% at steeper inclines (6% and 8%).
• Running at a fixed Stryd power yielded 'relatively consistent indications of metabolic demand across incline conditions.'
• The consistency of perceptual and physiological responses (heart rate, RPE, ventilation) across inclines supports the practical utility of the Stryd device for training intensity guidance.
• The study population consisted of trained runners with a mean VO2max of 55.9 (9.1) mL/kg/min.