Total kinetic energy production of body segments is different between racing and training paces in elite Olympic rowers.

Total kinetic energy (TKE) was calculated for 28 Canadian national team Olympic rowers during training on water, comparing low-stroke rates (18-22 stroke/min) and high-stroke rates (32-40 stroke/min), using video analysis. Stroke duration was normalized to 100%, beginning and ending at the "catches", with the drive phase occurring first and recovery second. Two discrete points were identified during the stroke, both occurring when the fingers had the same horizontal position as the ankles (i.e., mid-drive and mid-recovery). The ratios of recovery-to-drive TKE at these points for the entire body at low and high-stroke rates were 0.36 +/- 0.34 and 1.26 +/- 0.54 respectively. Significant differences were found for the lower leg, upper arm and forearm segments, and within the female groups. Low-stroke rate is a typical training pace and high-stroke rate is analogous to a race pace. This study demonstrates that TKE production during recovery in a race was not replicated during training. While training at low-stroke rates is vital for technique refinement, this study stresses the importance of training appropriately for the energy expenditure during high-stroke rate recovery. This is commonly overlooked by coaches and athletes.

Toe-out, lateral trunk lean, and pelvic obliquity during prolonged walking in patients with medial compartment knee osteoarthritis and healthy controls.

OBJECTIVE: To compare the time-varying behavior of maximum toe-out angle, lateral trunk lean (over the stance leg), and pelvic obliquity (rise and drop on the swing leg) during prolonged walking in participants with and without medial compartment knee osteoarthritis (OA), and to explore correlations between these gait characteristics and pain. METHODS: Twenty patients with knee OA and 20 healthy controls completed 30 minutes of treadmill walking. Toe-out, trunk lean, pelvic obliquity, and pain were measured at 5-minute intervals. RESULTS: The mean ± SD toe-out angle was significantly smaller (P = 0.04) in patients with knee OA (6.7 ± 2.5 degrees) than in controls (10.3 ± 2.2 degrees). Toe-out changed significantly over time (P = 0.002), but not in a systematic way, and there was no interaction between group and time. The mean ± SD trunk lean was higher (P = 0.03) in patients with knee OA (2.0 ± 1.0 degrees) than in controls (0.7 ± 0.5 degrees). Trunk lean did not change over time and there was no interaction between group and time. There were no differences for pelvic drop. The mean ± SD pelvic rise was higher (P = 0.01) in patients with knee OA (2.8 ± 0.9 degrees) than in controls (1.2 ± 0.8 degrees), but did not change over time and there was no interaction. Patients experienced a small increase in pain (P < 0.001). Trunk lean and pelvic drop were correlated with pain (r = 0.49, P = 0.03 and r = 0.47, P = 0.04, respectively). CONCLUSION: Toe-out and trunk lean are consistently different between individuals with and without medial compartment knee OA during prolonged walking, and patients with greater pain have greater trunk lean. However, over 30 minutes of walking, these gait characteristics remain quite stable, suggesting they are not acute compensatory mechanisms in response to repetitive loading with subtle increases in pain.

Time-varying behaviour, test-retest reliability and concurrent validity of lateral trunk lean and toe-out angles during prolonged treadmill walking.

Lateral trunk lean over the stance limb and toeing-out are potential adaptive gait mechanisms that reduce knee joint loading. The purpose of the present study was to evaluate the time-varying behaviour, the test-retest reliability and the concurrent validity of lateral trunk lean angle and toe-out angle during prolonged walking in healthy adults. Twenty healthy volunteers (51±8 years, 12 females) completed two test sessions at least 24h apart but within the same week. For each participant, at each session, three-dimensional gait kinematics were assessed intermittently during 60min of treadmill walking. Additionally, over-ground three-dimensional gait analysis was performed immediately before and after the treadmill walking. Maximum lateral trunk lean angle and maximum toe-out angle did not change over time (p>0.05), were consistent from day to day (test-retest reliability: ICC=0.61-0.72 and 0.90-0.95, respectively) and were consistent with over-ground measures (concurrent validity: ICC=0.88 and 0.92, respectively). These findings suggest that lateral trunk lean angle and toe-out angle are consistent during prolonged walking and that these measures are reliable and valid for use in studying adaptive gait mechanisms.