• Cardiovascular disease risk factors in habitual exercisers, lean sedentary men and abdominally obese sedentary men.

      O'Donovan, G.; Owen, A.; Kearney, E. M.; Jones, D. W.; Nevill, Alan M.; Woolf-May, K.; Bird, Steve (nature.com, 2005)
      OBJECTIVE: To investigate whether the favourable cardiovascular disease (CVD) risk factor profile of habitual exercisers is attributable to exercise or leanness. DESIGN: Cross-sectional study of 113 nonsmoking men aged 30-45 y. CVD risk factors were compared in exercisers (n=39) and sedentary men (n=74), and in subgroups of lean exercisers (n=37), lean sedentary men (n=46) and obese sedentary men (n=28). Waist girth was used to identify lean (<100 cm) and abdominally obese (> or =100 cm) subgroups. MEASUREMENTS: Blood pressure, physical activity (7-day recall), physical fitness (maximum oxygen consumption) and fasted lipoproteins, apolipoprotein (apo) B, triglycerides, glucose and fibrinogen. RESULTS: Exercisers were fitter and leaner than sedentary men and had a better CVD risk factor profile. Total cholesterol, LDL-cholesterol and apo B concentrations were lower in lean exercisers than in lean sedentary men, suggesting that exercise influences these risk factors. Indeed, time spent in vigorous activity was the only significant predictor of total cholesterol and LDL-cholesterol in multiple linear regression models. Exercise status had little influence on triglycerides and HDL-cholesterol (HDL-C), and unfavourable levels were only evident among obese sedentary men. Waist girth was the sole predictor of triglycerides and HDL-C, explaining 44 and 31% of the variance, respectively. CONCLUSIONS: These findings suggest that the CVD risk factor profile of habitual exercisers is attributable to leanness and exercise. Leanness is associated with favourable levels of HDL-C and triglycerides, while exercise is associated with lower levels of total cholesterol, LDL-cholesterol and apo B.
    • Different patterns of brisk walking are equally effective in decreasing postprandial lipaemia.

      Murphy, Marie H.; Nevill, Alan M.; Hardman, Adrianne E. (MCB University Press (Emerald), 2000)
      OBJECTIVE: To compare the effects of different patterns of brisk walking on day-long plasma triacylglycerol concentrations in sedentary adults. DESIGN: A three-trial, repeated measures design in which subjects were studied in the fasted state and throughout a day during which they consumed three standardized, mixed meals. On different occasions, subjects undertook no exercise (control), walked briskly for 10 min before each meal (short walks) or walked briskly for 30min before breakfast (long walk). SUBJECTS: Seven postmenopausal sedentary women and three sedentary men aged between 34 and 66y, with body mass index between 24 and 35 kg/m2. MEASUREMENTS: Plasma concentrations of triacylglycerol, non-esterified fatty acids, glucose and insulin, metabolic rate and whole-body substrate oxidation in the fasted state and at hourly intervals for 3 h after each meal. RESULTS: Postprandial plasma triacylglycerol concentrations were lower (P= 0.009) during the walking trials than during the control trial (average values: control 2.08 +/- 0.28 mmol/l; short walks 1.83 +/- 0.22mmol/l; long walk 1.84 +/- 0.22mmol/l (mean+/-s.e.) but did not differ between the two patterns of walking. The difference between control and walking trials increased as successive meals were consumed (interaction of trial x meal P= 0.03). Plasma triacylglycerol concentration increased during the 3 h after breakfast, changed little after lunch and decreased after the evening meal (interaction of meal x time P=0.001). When both walking trials were treated as one condition, walking increased postprandial fat oxidation (average values: control, 0.066 +/- 0.009 g/min;walking 0.074 +/- 0.008 g/min; P < 0.01). CONCLUSIONS: Thirty minutes of brisk walking, undertaken in one session or accumulated throughout a day, reduces postprandial plasma triacylglycerol concentrations and increases fat oxidation.
    • Effect of the Rotor crank system on cycling performance

      Jobson, Simon A.; Hopker, James; Galbraith, Andrew; Coleman, Damian A.; Nevill, Alan M. (2009)
      The aim of this study was to evaluate the impact of a novel crank system on laboratory time-trial cycling performance. The Rotor system makes each pedal independent from the other so that the cranks are no longer fixed at 180°. Twelve male competitive but non-elite cyclists (mean ± s: 35 ± 7 yr, Wmax = 363 ± 38 W, VO2peak = 4.5 ± 0.3 L·min-1) completed 6-weeks of their normal training using either a conventional (CON) or the novel Rotor (ROT) pedal system. All participants then completed two 40.23-km time-trials on an air-braked ergometer, one using CON and one using ROT. Mean performance speeds were not different between trials (CON = 41.7 km·h-1 vs. ROT = 41.6 km·h-1, P > 0.05). Indeed, the pedal system used during the time-trials had no impact on any of the measured variables (power output, cadence, heart rate, VO2, RER, gross efficiency). Furthermore, the ANOVA identified no significant interaction effect between main effects (Time-trial crank system*Training crank system, P > 0.05). To the authors' knowledge, this is the first study to examine the effects of the Rotor system on endurance performance rather than endurance capacity. These results suggest that the Rotor system has no measurable impact on time-trial performance. However, further studies should examine the importance of the Rotor 'regulation point' and the suggestion that the Rotor system has acute ergogenic effects if used infrequently.