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We studied the relationship between the speed at the gas exchange thresholds for walking and running and the preferred gait transition speed (PTS), and the correspondence of PTS and energetically optimal transition speed (EOTS). Twenty-two men (age: 21.4+/-2.4 years, mass: 78.1+/-8.2 kg) performed four tests during which we determined VO (2max), walking/running gas exchange thresholds, walk-to-run/run-to-walk PTS, and EOTS. There were no significant differences ( P>0.05) between PTS, and the speed at the aerobic threshold for walking (AeT (w)) and running (AeT (r)). Both walk-to-run and run-to-walk PTS significantly correlated to AeT (r) (r=0.82 and 0.79; P<0.01) but not to AeT (w) (r=-0.03 and 0.06; P>0.05). Finally, EOTS and the corresponding VO (2) were significantly higher ( P<0.05) than the speed and VO (2) at PTS. Our results indicate that running rather than walking dynamics determines gait transitions in men.

The aim of this study was to assess the validity of a fast ramp treadmill protocol for determination of the heart rate deflection point (HR (dp)) and speed of deflection (S (dp)) in trained runners. Fifty-one trained male runners performed a standard (T (stand); speed increase 1 km . h (-1) every 60 s) and a fast (T (fast); speed increase 1 km . h (-1) every 30 s) incremental treadmill test until volitional exhaustion. Heart rate was continuously recorded, and the HR (dp) was estimated after data averaging as the point of deflection in the linear speed/HR relationship. The HR (dp) and S (dp) recorded in T (fast) were compared with the corresponding values obtained in T (stand) by examining the Student's T-test, correlation coefficient (r), and limits of agreement (LoA). The HR (dp) recorded during standard and fast treadmill protocol were highly correlated (r = 0.92, p < 0.001) and similar to each other (p = 0.79). In contrast, S (dp) was highly correlated (r = 0.91, p < 0.001), but increased significantly with the faster ramp function (p < 0.001). No evidence of systematic bias was evident in the HR (dp) (95 % LoA of 0.2 +/- 7.3 bpm), while a uniform, systematic bias was evident for S (dp) in the T (fast) (95 % LoA of 1.6 +/- 1.5 km x h (-1)). We conclude that a fast ramp treadmill protocol (speed increase 1 km x h (-1) every 30 s) may be used for determination of the HR (dp) in trained runners, while S (dp) is protocol dependent and caution is warranted regarding its practical applicability.

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The purpose of this study was to assess the relationship between heart rate deflection point (HRDP) and ventilatory threshold (VT) to the physiological and performance variables in a relatively large group of trained men rowers. We proposed the hypothesis that physiological and performance variables corresponding to HRDP are not significantly different from corresponding variables at VT, which would justify the use of HRDP as a simple, affordable, and noninvasive method of anaerobic threshold assessment in trained rowers. Eighty-nine trained men rowers (mean ± SD: age 21.2 ± 4.1 years; stature 1.89 ± 0.06 m; body mass 89.2 ± 8.4 kg; VO₂max [maximum oxygen uptake] 5.39 ± 0.62 L/min⁻¹) completed an incremental rowing ergometer exercise test to exhaustion. Three independent, experienced observers determined both HRDP and VT. HRDP was determined by visual and computer-aided regression analyses and was evident in all rowers. The main findings include (a) there is a strong relationship among all observed physiological and performance variables corresponding to HR(HRDP) and HR(VT) (r = 0.79-0.96; p < 0.001) and (b) power output, oxygen uptake, ventilation, tidal volume and breathing rate corresponding to HR(HRDP) and HR(VT) were not significantly different (p ≥ 0.011), whereas HR(HRDP) was slightly but significantly higher than HR(VT) (174.5 vs. 172.8 beats·min⁻¹; p = 0.003). The standard error of the estimate in predicting the HR(VT) based on HR(HRDP) was 5.1 beats·min⁻¹. The subsequent data suggest that, in general, trained rowers may be able to periodically assess their aerobic endurance and evaluate the effects of training programs using the HRDP method.