Journal of Sports Medicine & Doping Studies

The aim of this study was to assess the reliability of a novel field test of critical running speed (CS). Ten trained male distance runners completed a familiarisation trial plus three separate experimental trials on a standard 400 m athletics track. Each trial consisted of three distances (1200, 2400 and 3600 metres) that were selected to produce finishing times in the region of 3, 7 and 12 minutes respectively. Participants were instructed to cover the set distance in the fastest time possible. Participants rested for 30 minutes between efforts. Data were modelled using the linear distance-time model, described by the equation: d = (CS x t) + ARC, where: d = distance run (m), t = running time (s), and ARC = anaerobic running capacity (m). Results demonstrated a coefficient of variation (CV) of 2.0% (95% confidence limit (95% CL): 1.4–3.8%) for trials 2–1 and 1.3% (95% CL: 0.9–2.4%) for trials 3–2. There was no significant difference in CS (m·s -1 ) across trials (P<0.05). The limits of agreement were ±0.27m·s -1 of the measure for trials 2–1 and ±0.18 m·s -1 for trials 3–2. ARC proved to be less reliable with a group CV of 18.4% (95% CL: 13.5– 39.9%) for trials 2–1 and 9.8% (95% CL: 7.0–19.6%) for trials 3–2. Although the assessment of ARC is less reliable, CV data are similar to those reported previously during laboratory-based testing.

Background: Habitual physical activity (PA) is associated with higher cardiorespiratory fitness values, but additional information is needed on the contributions of specific types and amounts of PA. Therefore the main aim of this study was to analyze the heart and lung function of a large cohort of men and compare these outcomes with various modes and volumes of PA. Methods: We used data from 30,594 men from the Aerobics Center Longitudinal Study who were categorized into sedentary, swimmer, walker, and runner groups using self-report PA data collected during 1970-2005. Additional PA categories using MET-minutes/week were used to group men into 5 distinct levels of activity (0 MET-min, 1-499 MET-min, 500-999 MET-min, 1000-1499 MET-min, and ? 1500 MET-min). Each participant also completed a maximal treadmill exercise test to quantify their fitness level. Cross-sectional analyses included general linear modeling and multiple comparisons adjusted for age, smoking status, and histories of myocardial infarction, stroke, diabetes, and hypertension. Results: A dose-response linear effect was found for heart function variables across PA MET-min categories. Stronger associations for resting heart rate (HR), heart rate recovery (HRR), exercise HR, and exercise blood pressure were found with the runner and swimming groups when compared to the walkers and sedentary groups. Walkers had significantly better heart function than the sedentary group but only about half the effect seen in the swimmers and runners. Lung function findings showed greater absolute values in FVC and FEV1 across PA categories, but found no difference in lung function ratios (e.g FEV1/FVC%). Conclusions: We found beneficial linear associations with resting HR, exercise HR, HRR, fitness values, FVC, and FEV1 over increasing MET-min categories. This implies that habitual PA, such as walking, but especially swimming and running, when performed with adequate volume, are viable ways to gain benefits for heart health.