5-km Time trial reliability of a non-motorized treadmill and comparison of physiological and perceptual responses versus a motorized treadmill
This study examined the reproducibility of performance across 3 non-motorized treadmill (NMT) 5-km time trials (TT) and physiological, gait, and perceptual differences of running at 5-km pace for both NMT and motorized treadmills (MT). Ten male runners experienced in road racing that had never run on a NMT completed 3 TT to establish personal best 5-km pace. In a later session, participants ran at this pace for 5 min on the NMT while metabolic, gait, and perceptual measures were recorded and then ran at outdoor 5-km personal best pace on a MT at 1% grade (counter-balanced crossover design). Intraclass correlation (ICC = 0.95) between the TT1 and TT2 was strong, but improved between TT2 and TT3 (ICC = 0.99) with considerable reduction in variability. NMT resulted in a 24% slower pace (10.6±1.5 vs 13.9±2.6 km/h; p < 0.001), shorter stride length (1.02±0.10 vs 1.27±0.18 m; p < 0.001), and decreased cadence (175±12 vs 181±13 steps/min; p = 0.01). However, V[Combining Dot Above]O2, RER, lactate concentration, and heart rate did not differ between modalities (NMT = 3.4±0.4 L/min, 0.96±0.04, 6.9±3.7 mmol, 172±10 bpm; MT = 3.4±0.5 L/min, 0.96±0.04, 5.7±3.4 mmol, 170±10 bpm). RPE for legs, breathing, and overall did not differ between treadmill types. A familiarization session should be included for TT using NMT. Other than gait and pace characteristics similar responses were elicited by both treadmills when running at 5-km pace. However, with these considerations NMT TT of 4-km might be more appropriate in matching MT 5-km TT duration without altering physiological responses significantly.