Prediction of energy expenditure from heart rate monitoring during submaximal exercise.

The aims of this study were to quantify the effects of factors such as mode of exercise, body composition and training on the relationship between heart rate and physical activity energy expenditure (measured in kJ x min(-1)) and to develop prediction equations for energy expenditure from heart rate. Regularly exercising individuals (n = 115; age 18-45 years, body mass 47-120 kg) underwent a test for maximal oxygen uptake (VO2max test), using incremental protocols on either a cycle ergometer or treadmill; VO2max ranged from 27 to 81 ml x kg(-1) x min(-1). The participants then completed three steady-state exercise stages on either the treadmill (10 min) or the cycle ergometer (15 min) at 35%, 62% and 80% of VO2max, corresponding to 57%, 77% and 90% of maximal heart rate. Heart rate and respiratory exchange ratio data were collected during each stage. A mixed-model analysis identified gender, heart rate, weight, V2max and age as factors that best predicted the relationship between heart rate and energy expenditure. The model (with the highest likelihood ratio) was used to estimate energy expenditure. The correlation coefficient (r) between the measured and estimated energy expenditure was 0.913. The model therefore accounted for 83.3% (R2) of the variance in energy expenditure in this sample. Because a measure of fitness, such as VO2max, is not always available, a model without VO2max included was also fitted. The correlation coefficient between the measured energy expenditure and estimates from the mixed model without VO2max was 0.857. It follows that the model without a fitness measure accounted for 73.4% of the variance in energy expenditure in this sample. Based on these results, we conclude that it is possible to estimate physical activity energy expenditure from heart rate in a group of individuals with a great deal of accuracy, after adjusting for age, gender, body mass and fitness.

Effects of a novel bicycle saddle on symptoms and comfort in cyclists.

BACKGROUND: While the bicycle frame and other parts of the bicycle have undergone many improvements, the bicycle saddle has remained relatively unchanged since it was first designed more than 100 years ago. Given the number and range of cycling injuries believed to result from the saddle, this is surprising. This study investigated the effects of a novel bicycle saddle on saddle-related comfort and symptoms during cycling. METHOD: Eleven competitive or recreational cyclists, 6 females and 5 males, performed three 2-hour stationary cycle rides in the laboratory, using their personal bicycles. Ride 1 was performed using the standard bicycle saddle and rides 2 and 3 using the novel bicycle saddle. Subjects reported saddle comfort rating scores (SC) while using the different saddles. Subjects also completed a questionnaire evaluating saddle symptoms (SS) when using either the conventional or the novel bicycle saddle during daily cycling. RESULTS: The most common saddle-related medical complaint with chronic use of the conventional saddle was painful pubic bones, with or without chaffing. Others were severe chaffing, saddle sores, chaffing and back pain, and painful pubic bones associated with a loss of feeling in the pelvic area. The mean SS rating score during the 2-hour laboratory ride was significantly less for the novel saddle (11.6 +/- 1.2 versus 19.1 +/- 3.2 arbitrary units, P < 0.01). Similarly the mean SC score was significantly lower for the novel saddle (36.2 +/- 10.5 v. 54.7 +/- 11.2 arbitrary units). Values for both SC scores were similar for rides 2 and 3. On completion of the trial all subjects indicated that they would continue to use the novel saddle in preference to the conventional saddle. Three months later 9 subjects (82%) reported continued use of this saddle in preference to the conventional saddle. CONCLUSION: These results show conclusively that this novel bicycle saddle: (i) significantly reduced reported symptoms during daily cycling compared with the conventionally designed cycling saddle; (ii) significantly improved saddle comfort during 2-hour cycles in the laboratory, such that (iii) when given the option the majority (82%) of the subjects chose to use this saddle 3 months later. Furthermore, the beneficial effects of the novel saddle were apparent during its first use, suggesting that the novel saddle is effective because the design is anatomically correct.

Free living energy expenditure in post menopausal women before and after exercise training.

The aim of the study was to determine the effects of 8 weeks of moderate exercise training, on 24-hour free living energy expenditure in previously sedentary post-menopausal women. The experimental group (EX) included 9 women. Ten non-exercising control subjects (CON) were recruited to undergo pre- and post-testing. Estimated total daily energy expenditure (TDEE), total 24-hour heart beats (HB), total energy intake (TEI), resting metabolic rate, maximal oxygen consumption (VáO2max), body composition, and submaximal heart rate were measured before and after the exercise intervention. Body composition did not change (body fat % in CON 34.0 +/- 4.0% vs. 33.9 +/- 3.6% and EX 34.1 +/- 4.0% vs. 34.0 +/- 3.4%). Mean submaximal heart rate during steady-state exercise in EX was lower after training compared to CON (p < .05); however, VáO2max did not increase significantly (CON 1.96 +/- 0.23 vs. 1.99 +/- 0.24 l L O2/min and EX 1.86 +/- 0.39 vs. 1.94 +/- 0.30 L O2/min). Neither estimated TDEE (CON, 11.6 +/- 2.0 vs. 11.4 +/- 2.78 MJ; and EX 11.4 +/- 3.3 vs. 11.5 +/- 2.5 MJ, pre vs. post, respectively), RMR (CON 134.2 +/- 9.4 vs. 136.9 +/- 15.0 KJ/kgFFM/day, and EX 138.4 +/- 6.4 vs. 140.7 +/- 14.2 KJ/kgFFM/day, pre vs. post, respectively), TEI (CON 7.9 +/- 2.2 vs. 8.2 +/- 2.5 MJ, and EX 9.4 +/-1.6 vs. 8.3 +/- 2.8 MJ), nor HB (CON 110,808 +/- 12,574 vs. 107,366 +/- 12,864 beats, and EX 110,188 +/- 9,219 vs. 114,590 +/- 12,750 beats) change over 8 weeks in either group. These data suggest that a moderate exercise program may not impact on TDEE, RMR, TEI, or HB in previously sedentary, older women.