A replicate crossover trial on the inter-individual variability of sleep indices in response to acute exercise undertaken by healthy men

Study objective: Using the necessary replicate-crossover design, we investigated whether there is inter-individual variability in home-assessed sleep in response to acute exercise.Methods: Eighteen healthy men (mean(SD): 26(6) years) completed two identical control (8-h laboratory rest, 08:45-16:45) and two identical exercise (7-h laboratory rest; 1-h laboratory treadmill run [62(7)% peak oxygen uptake], 15:15-16:15) trials in randomised sequences. Wrist-worn actigraphy (MotionWatch 8) measured home-based sleep (total sleep time, actual wake time, sleep latency, sleep efficiency) two nights before (nights 1-2) and three nights after (nights 3-5) the exercise/control day. Pearson’s correlation coefficients quantified the consistency of individual differences between the replicates of control-adjusted exercise responses to explore: (1) immediate (night 3 minus night 2); (2) delayed (night 5 minus night 2); and (3) overall (average post-intervention minus average pre-intervention) exercise- related effects. Within-participant linear mixed models and a random-effects between- participant meta-analysis estimated participant-by-trial response heterogeneity.Results: For all comparisons and sleep outcomes, the between-replicate correlations were non-significant, ranging from trivial-to-moderate (r range = -0.44 to 0.41, P≥0.065). Participant-by-trial interactions were trivial. Individual differences SDs were small, prone to uncertainty around the estimates indicated by wide 95% confidence intervals and did not provide support for true individual response heterogeneity. Meta-analyses of the between-participant, replicate-averaged condition effect revealed that, again, heterogeneity (τ) was negligible for most sleep outcomes.Conclusion: Control-adjusted sleep in response to acute exercise was inconsistent when measured on repeated occasions. Inter-individual differences in sleep in response to exercise4 were small compared to the natural (trial-to-trial) within-subject variability in sleep outcomes.</p

Acute Running and Coronary Heart Disease Risk Markers in Male Cigarette Smokers and Nonsmokers: A Randomized Crossover Trial.

Purpose Cigarette smoking is an independent risk factor for coronary heart disease (CHD) and is associated with impaired postprandial metabolism. Acute exercise reduces postprandial lipemia and improves other CHD risk markers in non-smokers. Less is known about responses in cigarette smokers.Methods Twelve male cigarette smokers (mean(SD) age 23(4) years, BMI 24.9(3.0) kg/m2) and 12 male non-smokers (24(4) years, 24.1(2.0) kg/m2) completed two, 2-day conditions (control, exercise) in a randomised, crossover design. On day 1, participants rested for 9-hours (08:00-17:00) in both conditions except a 60-minute treadmill run (65(7)% peak oxygen uptake, 2.87(0.54) MJ) was completed between 6.5-7.5 h (14:30-15:30) in the exercise condition. On day 2 of both conditions, participants rested and consumed two high-fat meals over 8-hours (09:00-17:00) during which 13 venous blood samples and nine resting arterial blood pressure measurements were taken.Results Smokers exhibited higher postprandial triacylglycerol and C-reactive protein than non-smokers (main effect group effect size (Cohen’s d)≥0.94, P≤0.034). Previous day running reduced postprandial triacylglycerol, insulin and systolic and diastolic blood pressure (main effect condition d≥0.28, P≤0.044), and elevated postprandial non-esterified fatty acid and C-reactive protein (main effect condition d≥0.41, P≤0.044). Group-by-condition interactions were not apparent for any outcome across the total postprandial period (0-8 h; all P≥0.089), but the exercise-induced reduction in postprandial triacylglycerol in the early postprandial period (0-4 h) was greater in non-smokers than smokers (-21% (d=0.43) vs -5% (d=0.16), respectively; group-by-condition interaction P=0.061).Conclusions Acute moderate-intensity running reduced postprandial triacylglycerol, insulin and resting arterial blood pressure the day after exercise in male cigarette smokers and non-smokers. These findings highlight the ability of acute exercise to augment the postprandial metabolic health of cigarette smokers and non-smokers.</div