Type 2 diabetes increases bone fracture risk in postmenopausal women. Usual treatment with anti-resorptive bisphosphonate drugs has some undesirable side effects, which justified our interest in the osteogenic potential of nutrition and exercise. Since meal eating reduces bone resorption, downhill locomotion increases mechanical stress, and brief osteogenic responsiveness to mechanical stress is followed by several hours of refractoriness, we designed a study where 40-min of mechanical stress was manipulated by treadmill walking uphill or downhill. Exercise preceded or followed two daily meals by one hour, and the meals and exercise bouts were 7 hours apart. Fifteen subjects each performed two of five trials: No exercise (SED), uphill exercise before (UBM) or after meals (UAM), and downhill exercise before (DBM) or after meals (DAM). Relative to SED trial, osteogenic response, defined as the ratio of osteogenic C-terminal propeptide of type I collagen (CICP) over bone-resorptive C-terminal telopeptide of type-I collagen (CTX) markers, increased in exercise-after-meal trials, but not in exercise-before-meal trials. CICP/CTX response rose significantly after the first exercise-after-meal bout in DAM, and after the second one in UAM, due to a greater CICP rise, and not a decline in CTX. Post-meal exercise, but not the pre-meal exercise, also significantly lowered serum insulin response and homeostatic model (HOMA-IR) assessment of insulin resistance.

Data indicate that as little as 3 weeks of moderate treadmill exercise reduces plasma and fundus total ghrelin concentrations with elevated plasma GH and liver ATP content occurring after 6 and 12 weeks of training. Exercise training-induced improvement of energy source availability and negative feedback from increased GH levels may play a role in reducing plasma and fundus ghrelin levels.

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Structural integrity of bones is supported by mechanical loading, energy intake, and sex hormones. It is unclear why postmenopausal (PM) diabetics experience more bone breaks despite higher body weight and positive energy balance than non-diabetics. We hypothesized that greater bone fragility in PM diabetics may result from peripheral insulin resistance and reduced nutrient access to the bone. We engaged 15 diabetic women, age 57.7y, BMI 27.2 kg/m 2 , in two of five day-long experiments : SED (no exercise), UBM and UAM (40 min of uphill treadmill exercise, respectively one h before, or one h after eating two daily isocaloric meals at 10 and 17 h and containing 50% carbohydrate, 15% protein, and 25% fat), and DBM and DAM (downhill exercise at -6 o slope with meals and exercise timed the same way). Markers of bone formation osteocalcin (OCN) and CICP (c-terminal propeptide of type I collagen) and of resorption, CTX (c-terminal telopeptide of type I collagen), anabolic growth hormone and catabolic cortisol were measured hourly in the serum. Glucose and insulin were measured to assess insulin resistance by the homeostatic HOMA-IR method from 7-h postprandial (PP) insulin and glucose areas under the curve (AUCs).Peak ground-reaction forces (GRFs) were monitored with Novel Pedar mechanosensitive shoe insoles, and physical effort was assessed as percent of VO 2 max with a metabolic cart. During uphill trials, mean effort was 75.2% , and GRFs were 780.7 N. During downhill trials, the corresponding values were 47.9% of VO 2 max and 1104.8 N (both >0.05). A similar CTX decline in all 5 trials after the 10h meal was larger than after the 17 h meal (7h negative PP AUCs: 1.52 vs 1.37 ng/ml*h, respectively) and coincided with PP insulin AUCs. CICP rise in DAM trial was 44% greater than in DBM trial after 10h meal (AUCs, 685.9 vs 384.1 ng/ml*h, respectively) and produced a 40 percent greater osteogenic CICP/CTX ratio after 10h meal in the in the DAM than DBM trial. No group difference was seen in brief postprandial serum glucose rises, while PP insulin was highest in UBM and SED trials and low in the two downhill and UAM trials. HOMA-IR in the two downhill trials (355.6) was reduced to 47% of that in two uphill trials (759.1) and to 62% of the SED trial (571.4). Circulating OCN and hormones showed no clear relationship to either the loading or meal-exercise timing patterns. We conclude that In PM diabetics, downhill (as opposed to uphill) exercise after a meal conveys a clear benefit in stimulating a bone- forming CICP, more so after the 10h than the 17 h meal. Meal eating, independently of exercise, lowers the bone resorption marker CTX. In diabetic PM women, Increased GRFs of downhill exercise reduce HOMA-IR insulin resistance to high-carbohydrate meals more than uphill exercise or SED control. Postprandial downhill exercise has the highest osteogenic potential.

The goal of this study was to assess the effects of amount of ergometer cycle training on Vo 2 max and body composition in overweight women. Forty-one sedentary premenopausal women, age 25 to 45 years, were randomly assigned in three groups. Cycle ergometer training consisted of one day per week for group A, two days per week for group B and three days per week for group C. Participants trained for 60 min in any session with moderate intensity (50-60% Vo 2 max) for 12 weeks. Participants were counseled not to change their diet during the study period. There were no significant differences among variables in three groups at baseline. Means (±SD) of weight, body fat, WHR, BMI and Vo 2 max in groups were 67.43±9.54kg, 31.56±4.6 percent, 0.82±0.05, 25.54±4.16 kg/m 2 and 31.72±7.2 ml.kg -1 min -1 respectively. After 12 weeks, ANOVA test indicated there were significant differences among mean body composition among the three groups. Use of Tukey post-hoc tests showed that difference in theses groups is because of group C. Paired 't' test showed that there was significant difference between mean body composition (p<0.01) in group C. Vo 2 max in group B and C improved 12% and 21% (p<0.01) respectively with ergometer training. But in group A it was not changed significantly. These findings indicate that the three days in week with 60 min of moderate-intensity, cycle ergometer training is sufficient to improve body composition and Vo 2 max in over weight women. With two days training i.e. 120 min in a week only, Vo 2 max improved. The results indicate that two days regular training improves Vo 2 max in overweight women without change in body composition. With less of amount of physical activity neither body composition nor Vo 2 max improve significantly. These findings strongly suggest that, in the absence of changes in diet, a higher amount of activity is necessary for improving body composition and Vo 2 max.