The relationship between gait transition speed and the aerobic thresholds for walking and running.

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.

Validity of the modified Conconi running test.

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.