Guest guest Posted October 5, 2005 Report Share Posted October 5, 2005 Dont know if this was posted yet.. Jeff Am J Physiol Endocrinol Metab. 2005 Sep;289(3):E446-55. Epub 2005 May 3. Related Three weeks of caloric restriction alters protein metabolism in normal-weight, young men. Geriatric Research Education and Clinical Center and Research and Medical Services, Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304, USA. friedlan@... The effects of prolonged caloric restriction (CR) on protein kinetics in lean subjects has not been investigated previously. The purpose of this study was to test the hypotheses that 21 days of CR in lean subjects would 1) result in significant losses of lean mass despite a suppression in leucine turnover and oxidation and 2) negatively impact exercise performance. Nine young, normal-weight men [23 +/- 5 y, 78.6 +/- 5.7 kg, peak oxygen consumption (Vo2 peak) 45.2 +/- 7.3 ml.kg(-1).min(-1), mean +/- SD] were underfed by 40% of the calories required to maintain body weight for 21 days and lost 3.8 +/- 0.3 kg body wt and 2.0 +/- 0.4 kg lean mass. Protein intake was kept at 1.2 g.kg(-1).day(-1). Leucine kinetics were measured using alpha-ketoisocaproic acid reciprocal pool model in the postabsorptive state during rest and 50 min of exercise (EX) at 50% of Vo2 peak). Body composition, basal metabolic rate (BMR), and exercise performance were measured throughout the intervention. At rest, leucine flux (approximately 131 micromol.kg(-1).h(-1)) and oxidation (R(ox); approximately 19 micromol.kg(-1).h(-1)) did not differ pre- and post-CR. During EX, leucine flux (129 +/- 6 vs. 121 +/- 6) and R(ox) (54 +/- 6 vs. 46 +/- 8) were lower after CR than they were pre-CR. Nitrogen balance was negative throughout the intervention ( approximately 3.0 g N/day), and BMR declined from 1,898 +/- 262 to 1,670 +/- 203 kcal/day. Aerobic performance (Vo2 peak, endurance cycling) was not impacted by CR, but arm flexion endurance decreased by 20%. In conclusion, 3 wk of caloric restriction reduced leucine flux and R(ox) during exercise in normal-weight young men. However, despite negative nitrogen balance and loss of lean mass, whole body exercise performance was well maintained in response to CR. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted October 5, 2005 Report Share Posted October 5, 2005 Jeff, I think that this is a VERY IMPORANT paper for CR (PMID: 15870104). Although the authors emphasize protein metabolism, what is really important for us is the fact that " BMR declined from 1,898 +/- 262 to 1,670 +/- 203 kcal/day " in 3 weeks of 40%CR. Unfortunately, the abstract does not have the average height or BMI of the people tested. From the average weight of 78.6 kg (173 lb) and a BMR of 1,898, I was able to deduce using Mifflin-St Jeor (M-SJ) equations that the average height of the 9 people tested was about 6 ft. 5 in., corresponding to an average BMI of 20.6. (I guess that the nine guys were probably basketball players.) Since the subjects lost 3.8 kg body weight (8.4 lb), their new average weight would have been 74.8 kg (164.6 lb) at the end of the experiment. The BMR calculated for the final lower weight is 1860 using M-SJ, whereas the BMR measured by the authors was 1670. This demonstrates an increase in metabolic efficiency of 190 calories (10.2%) as the body adapts to CR over 3 weeks. The experiment was of very short duration, and the negative nitrogen balance indicates that the subjects did not achieve nutritional equilibrium with the severe level of restriction, but it is interesting to see that the body starts adapting relatively fast to food restriction. Tony ======= > Dont know if this was posted yet.. > > Jeff > > Am J Physiol Endocrinol Metab. 2005 Sep;289(3):E446-55. Epub 2005 May 3. > Related > > Three weeks of caloric restriction alters protein metabolism in > normal-weight, young men. > > Geriatric Research Education and Clinical Center and Research and Medical > Services, Veterans Affairs Palo Alto Health Care System, Palo Alto, CA > 94304, USA. friedlan@s... > > The effects of prolonged caloric restriction (CR) on protein kinetics in > lean subjects has not been investigated previously. The purpose of this > study was to test the hypotheses that 21 days of CR in lean subjects would > 1) result in significant losses of lean mass despite a suppression in > leucine turnover and oxidation and 2) negatively impact exercise > performance. Nine young, normal-weight men [23 +/- 5 y, 78.6 +/- 5.7 kg, > peak oxygen consumption (Vo2 peak) 45.2 +/- 7.3 ml.kg(-1).min(-1), mean +/- > SD] were underfed by 40% of the calories required to maintain body weight > for 21 days and lost 3.8 +/- 0.3 kg body wt and 2.0 +/- 0.4 kg lean mass. > Protein intake was kept at 1.2 g.kg(-1).day(-1). Leucine kinetics were > measured using alpha-ketoisocaproic acid reciprocal pool model in the > postabsorptive state during rest and 50 min of exercise (EX) at 50% of Vo2 > peak). Body composition, basal metabolic rate (BMR), and exercise > performance were measured throughout the intervention. At rest, leucine flux > (approximately 131 micromol.kg(-1).h(-1)) and oxidation (R(ox); > approximately 19 micromol.kg(-1).h(-1)) did not differ pre- and post-CR. > During EX, leucine flux (129 +/- 6 vs. 121 +/- 6) and R(ox) (54 +/- 6 vs. 46 > +/- 8) were lower after CR than they were pre-CR. Nitrogen balance was > negative throughout the intervention ( approximately 3.0 g N/day), and BMR > declined from 1,898 +/- 262 to 1,670 +/- 203 kcal/day. Aerobic performance > (Vo2 peak, endurance cycling) was not impacted by CR, but arm flexion > endurance decreased by 20%. > > In conclusion, 3 wk of caloric restriction > reduced leucine flux and R(ox) during exercise in normal-weight young men. > However, despite negative nitrogen balance and loss of lean mass, whole body > exercise performance was well maintained in response to CR. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted October 5, 2005 Report Share Posted October 5, 2005 Jeff, I think that this is a VERY IMPORANT paper for CR (PMID: 15870104). Although the authors emphasize protein metabolism, what is really important for us is the fact that " BMR declined from 1,898 +/- 262 to 1,670 +/- 203 kcal/day " in 3 weeks of 40%CR. Unfortunately, the abstract does not have the average height or BMI of the people tested. From the average weight of 78.6 kg (173 lb) and a BMR of 1,898, I was able to deduce using Mifflin-St Jeor (M-SJ) equations that the average height of the 9 people tested was about 6 ft. 5 in., corresponding to an average BMI of 20.6. (I guess that the nine guys were probably basketball players.) Since the subjects lost 3.8 kg body weight (8.4 lb), their new average weight would have been 74.8 kg (164.6 lb) at the end of the experiment. The BMR calculated for the final lower weight is 1860 using M-SJ, whereas the BMR measured by the authors was 1670. This demonstrates an increase in metabolic efficiency of 190 calories (10.2%) as the body adapts to CR over 3 weeks. The experiment was of very short duration, and the negative nitrogen balance indicates that the subjects did not achieve nutritional equilibrium with the severe level of restriction, but it is interesting to see that the body starts adapting relatively fast to food restriction. Tony ======= > Dont know if this was posted yet.. > > Jeff > > Am J Physiol Endocrinol Metab. 2005 Sep;289(3):E446-55. Epub 2005 May 3. > Related > > Three weeks of caloric restriction alters protein metabolism in > normal-weight, young men. > > Geriatric Research Education and Clinical Center and Research and Medical > Services, Veterans Affairs Palo Alto Health Care System, Palo Alto, CA > 94304, USA. friedlan@s... > > The effects of prolonged caloric restriction (CR) on protein kinetics in > lean subjects has not been investigated previously. The purpose of this > study was to test the hypotheses that 21 days of CR in lean subjects would > 1) result in significant losses of lean mass despite a suppression in > leucine turnover and oxidation and 2) negatively impact exercise > performance. Nine young, normal-weight men [23 +/- 5 y, 78.6 +/- 5.7 kg, > peak oxygen consumption (Vo2 peak) 45.2 +/- 7.3 ml.kg(-1).min(-1), mean +/- > SD] were underfed by 40% of the calories required to maintain body weight > for 21 days and lost 3.8 +/- 0.3 kg body wt and 2.0 +/- 0.4 kg lean mass. > Protein intake was kept at 1.2 g.kg(-1).day(-1). Leucine kinetics were > measured using alpha-ketoisocaproic acid reciprocal pool model in the > postabsorptive state during rest and 50 min of exercise (EX) at 50% of Vo2 > peak). Body composition, basal metabolic rate (BMR), and exercise > performance were measured throughout the intervention. At rest, leucine flux > (approximately 131 micromol.kg(-1).h(-1)) and oxidation (R(ox); > approximately 19 micromol.kg(-1).h(-1)) did not differ pre- and post-CR. > During EX, leucine flux (129 +/- 6 vs. 121 +/- 6) and R(ox) (54 +/- 6 vs. 46 > +/- 8) were lower after CR than they were pre-CR. Nitrogen balance was > negative throughout the intervention ( approximately 3.0 g N/day), and BMR > declined from 1,898 +/- 262 to 1,670 +/- 203 kcal/day. Aerobic performance > (Vo2 peak, endurance cycling) was not impacted by CR, but arm flexion > endurance decreased by 20%. > > In conclusion, 3 wk of caloric restriction > reduced leucine flux and R(ox) during exercise in normal-weight young men. > However, despite negative nitrogen balance and loss of lean mass, whole body > exercise performance was well maintained in response to CR. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted October 6, 2005 Report Share Posted October 6, 2005 Hi All, Details are, from the available pdf: Friedlander AL, Braun B, Pollack M, Mac JR, Fulco CS, Muza SR, Rock PB, GC, Horning MA, GA, Hoffman AR, Cymerman A. Three weeks of caloric restriction alters protein metabolism in normal-weight, young men. Am J Physiol Endocrinol Metab. 2005 Sep;289(3):E446-55. Epub 2005 May 3. PMID: 15870104 http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve & db=pubmed & dopt=Abstra\ ct & list_uids=15870104 & query_hl=12 .... RESULTS Subject Characteristics, Diet, and Body Composition All nine normal-weight, recreationally fit young men (age, 23 ± 5 yr; weight, 78.6 ± 5.7 kg; height, 177 ± 8 cm; body fat, 16 ± 4%; lean mass, 65.4 ± 6.1 kg; O2 peak, 45.2 ± 7.3 ml·kg–1·min–1) completed the intervention period. Post hoc analysis of the diet indicated that the goal of 40% caloric restriction (1,300 kcal) was achieved (Table 1). Protein content of the diet remained relatively constant (between 1.1 and 1.2 g·kg–1·day–1), whereas the quantity of CHO was cut by 36 and 46%, respectively. Subjects lost an average of 3.8 ± 0.3 kg (5%) body wt over the 21-day intervention, with equal amounts coming from fat and fat-free tissue compartments (1.8 ± 0.4 and 2.0 ± 0.4, respectively; Fig. 1). Table 1. Mean daily caloric and macronutrient content of the diet ============== kcal CHO, g Protein, g Fat, g %Change, kcal ============== Baseline (days –7 to –1) 3,245±187 555±42 (68%) 92±8 (11%) 73±6 (21%) Hypocaloric (days 1 to 21) 1,950±260 299±34 (61%) 85±11 (18%) 46±6 (21%) –40% ============== Values are means ± SD (%total energy). CHO, carbohydrate. Protein set between 1.1 and 1.2 g/kg. Basal Metabolic Rate and NBAL Before caloric restriction, BMR was 1,900 kcal/day and declined 15% over the intervention period reaching a maximum reduction of 230 kcal/day on days 19–21 (Fig. 2). No significant association was observed between quantity of weight or lean mass lost and decline in BMR among individual subjects. NBAL data for the seven subjects who were able to provide complete 24-h urine collections are presented in Fig. 3. NBAL was negative at each of the measurement periods during the caloric restriction intervention, although the values tended to improve by days 10–12 compared with the first week of collections (Fig. 3). Although no baseline urine samples for these subjects were collected (see METHODS), baseline NBAL values from matched subjects (n = 16) undergoing identical testing and dietary controls are provided for comparison in Fig. 3. Protein Metabolism Studies Calorimetry data and metabolite concentrations. All values presented in Table 2 were measured during the last 15 min of rest (3.5 h postmeal) and the last 30 min of exercise during the isotope trials on days 1 and 18 of the intervention. During both trials, subjects worked at the same absolute (1.85 l/min) and relative (53% of O2 peak) workloads during the exercise bout for 50 min. Respiratory exchange ratio was higher during exercise than rest for both trials and tended to be reduced following caloric restriction (P = 0.06, day 1 vs. day 18 for rest and exercise). Leucine concentration was higher during exercise than rest on day 1 (P < 0.003) but not on day 18. There were no significant exercise or caloric restriction-induced differences in KIC concentration. Plasma glucose, lactate, and FFA all differed between rest and exercise but demonstrated no significant change in response to caloric restriction. In contrast, ß-hydroxybutyrate was elevated at both rest and exercise following 18 days of underfeeding (P < 0.002) but did not respond to the exercise stimulus (Table 2). Table 2. Gas exchange, metabolite, and hormone variables measured during isotope tests ================== Day 1 Day 18 Rest Exercise Rest Exercise ================== Day 1 Day 18 Rest Exercise Rest Exercise =================== V^O2, l/min 0.27±0.06 1.87±0.28† 0.27±0.03 1.82±0.28† RER 0.89±0.06 0.93±0.03† 0.85±0.06 0.90±0.03† Glucose, mM 4.8±0.6 4.4±0.6† 4.6±0.6 4.3±0.3† Lactate, mM 0.4±0.08 2.1±1.1† 0.4±0.08 1.5±0.6† FFA, mM 0.32±0.11 0.61±0.26† 0.36±0.25 0.74±0.20† Leucine, M 78.3±8.7 85.0±6.2† 77.6±12.6 76.5±7.3 KIC, M 10.6±3.1 12.7±5.6 11.5±2.5 11.3±4.2 ß-OHB, mM 0.78±0.57 0.90±0.60 1.66±0.60* 1.83±1.18* Insulin, pM 105±82 51±25† 74±35 37±9*† Cortisol, nM 251±104 328±154† 226±52 303±33† ================== Values are means ± SD. Exercise, last 30 min of a 50-minute exercise bout at 50% VO2max, RER, respiratory exchange ratio; FFA, free fatty acid; KIC, alpha-ketolsocaproate; ß-OHB, ß-hydroxybutyrate. * Significantly different from day 1 at P < 0.05. † Significantly different from rest at P < 0.05. KIC isotopic enrichments and leucine kinetics. Steady-state isotopic plateaus in KIC and 13CO2 were reached in both trials during the exercise sampling periods (Fig. 4, A and . Leucine flux did not differ between rest and exercise on day 1. However, 18 days of caloric restriction suppressed leucine flux during exercise relative to both rest on day 18 and exercise on day 1 (Fig. 5A). On days 1 and 18, leucine oxidation more than doubled between rest and exercise (19 vs. 50 µmol·kg–1·h–1). After 18 days of caloric restriction, leucine oxidation was reduced during exercise relative to day 1 exercise values (Fig. 5B). Nonoxidative leucine disposal was attenuated with exercise but was not affected by the caloric restriction (data not shown). Hormone responses during the isotope trials. Insulin concentration was lower during exercise compared with rest on both days 1 and 18, but the fall was greater during exercise on day 18 than on day 1 (Table 2). Exercise induced a significant increase in cortisol concentration during both trials, but there was no impact of dietary energy restriction on the cortisol response during rest or exercise (Table 2). Performance measurements. Performance test results are presented in Table 3. O2 peak did not change over the intervention period when expressed in liters per minute. However, it tended to increase when expressed relative to the declining body weight (ml·kg–1·min–1). Similarly, there was no significant effect of caloric restriction on submaximal endurance time on the cycle ergometer. Subjects experienced a mixed response to caloric restriction on the lift-and-carry vs. arm flexion test with a 12% improvement on the former, but a 20% decrement on the latter. There was a strong association between decrement in arm flexion performance and the quantity of weight lost during the intervention (r = 0.7, P > 0.05; Fig. 6A). When decrement in arm flexion performance was plotted as a function of percent change in body weight, the relationship was maintained with those losing more than 5% of their body weight, demonstrating the greatest reduction in performance (Fig. 6B). The relationship between change in arm flexion and fat-free mass was less robust [r = 0.5, not significant (NS)] and there was little association between improvements in lift-and-carry and change in either body weight or lean mass (r < 0.4, NS). Table 3. Exercise performance data collected during the 21-day intervention ================== Baseline Days 2–3 Days 10–11 Days 20–21 ================== V^O2max l/min 3.5±0.5 3.5±0.5 3.5±0.5 Submax endurance, # min 43.4±21.9 39.9±17.4 Arm flexion, no. of reps 26±6 25±5 26±10 20±8*† Lift and carry, min 5.7±0.7 5.4±0.8 5.2±0.9* 5.0±0.7* =================== Values are means ± SD. # Ride to exhaustion at 70% O2max. Test was performed immediately following the isotope trial of 50 min at 50% of O2max (actually measured on days 1 and 18). * Significantly different from baseline at P < 0.05. † Significantly different from days 2–3 at P < 0.05. .... These data are interpreted to mean that normal-weight individuals have less robust mechanisms to preserve lean mass than obese subjects but can still adapt to 3 wk of moderately severe caloric restriction in a way that minimizes decrements in physical performance. Al Pater, PhD; email: old542000@... __________________________________ - PC Magazine Editors' Choice 2005 http://mail. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted October 6, 2005 Report Share Posted October 6, 2005 Hi All, Details are, from the available pdf: Friedlander AL, Braun B, Pollack M, Mac JR, Fulco CS, Muza SR, Rock PB, GC, Horning MA, GA, Hoffman AR, Cymerman A. Three weeks of caloric restriction alters protein metabolism in normal-weight, young men. Am J Physiol Endocrinol Metab. 2005 Sep;289(3):E446-55. Epub 2005 May 3. PMID: 15870104 http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve & db=pubmed & dopt=Abstra\ ct & list_uids=15870104 & query_hl=12 .... RESULTS Subject Characteristics, Diet, and Body Composition All nine normal-weight, recreationally fit young men (age, 23 ± 5 yr; weight, 78.6 ± 5.7 kg; height, 177 ± 8 cm; body fat, 16 ± 4%; lean mass, 65.4 ± 6.1 kg; O2 peak, 45.2 ± 7.3 ml·kg–1·min–1) completed the intervention period. Post hoc analysis of the diet indicated that the goal of 40% caloric restriction (1,300 kcal) was achieved (Table 1). Protein content of the diet remained relatively constant (between 1.1 and 1.2 g·kg–1·day–1), whereas the quantity of CHO was cut by 36 and 46%, respectively. Subjects lost an average of 3.8 ± 0.3 kg (5%) body wt over the 21-day intervention, with equal amounts coming from fat and fat-free tissue compartments (1.8 ± 0.4 and 2.0 ± 0.4, respectively; Fig. 1). Table 1. Mean daily caloric and macronutrient content of the diet ============== kcal CHO, g Protein, g Fat, g %Change, kcal ============== Baseline (days –7 to –1) 3,245±187 555±42 (68%) 92±8 (11%) 73±6 (21%) Hypocaloric (days 1 to 21) 1,950±260 299±34 (61%) 85±11 (18%) 46±6 (21%) –40% ============== Values are means ± SD (%total energy). CHO, carbohydrate. Protein set between 1.1 and 1.2 g/kg. Basal Metabolic Rate and NBAL Before caloric restriction, BMR was 1,900 kcal/day and declined 15% over the intervention period reaching a maximum reduction of 230 kcal/day on days 19–21 (Fig. 2). No significant association was observed between quantity of weight or lean mass lost and decline in BMR among individual subjects. NBAL data for the seven subjects who were able to provide complete 24-h urine collections are presented in Fig. 3. NBAL was negative at each of the measurement periods during the caloric restriction intervention, although the values tended to improve by days 10–12 compared with the first week of collections (Fig. 3). Although no baseline urine samples for these subjects were collected (see METHODS), baseline NBAL values from matched subjects (n = 16) undergoing identical testing and dietary controls are provided for comparison in Fig. 3. Protein Metabolism Studies Calorimetry data and metabolite concentrations. All values presented in Table 2 were measured during the last 15 min of rest (3.5 h postmeal) and the last 30 min of exercise during the isotope trials on days 1 and 18 of the intervention. During both trials, subjects worked at the same absolute (1.85 l/min) and relative (53% of O2 peak) workloads during the exercise bout for 50 min. Respiratory exchange ratio was higher during exercise than rest for both trials and tended to be reduced following caloric restriction (P = 0.06, day 1 vs. day 18 for rest and exercise). Leucine concentration was higher during exercise than rest on day 1 (P < 0.003) but not on day 18. There were no significant exercise or caloric restriction-induced differences in KIC concentration. Plasma glucose, lactate, and FFA all differed between rest and exercise but demonstrated no significant change in response to caloric restriction. In contrast, ß-hydroxybutyrate was elevated at both rest and exercise following 18 days of underfeeding (P < 0.002) but did not respond to the exercise stimulus (Table 2). Table 2. Gas exchange, metabolite, and hormone variables measured during isotope tests ================== Day 1 Day 18 Rest Exercise Rest Exercise ================== Day 1 Day 18 Rest Exercise Rest Exercise =================== V^O2, l/min 0.27±0.06 1.87±0.28† 0.27±0.03 1.82±0.28† RER 0.89±0.06 0.93±0.03† 0.85±0.06 0.90±0.03† Glucose, mM 4.8±0.6 4.4±0.6† 4.6±0.6 4.3±0.3† Lactate, mM 0.4±0.08 2.1±1.1† 0.4±0.08 1.5±0.6† FFA, mM 0.32±0.11 0.61±0.26† 0.36±0.25 0.74±0.20† Leucine, M 78.3±8.7 85.0±6.2† 77.6±12.6 76.5±7.3 KIC, M 10.6±3.1 12.7±5.6 11.5±2.5 11.3±4.2 ß-OHB, mM 0.78±0.57 0.90±0.60 1.66±0.60* 1.83±1.18* Insulin, pM 105±82 51±25† 74±35 37±9*† Cortisol, nM 251±104 328±154† 226±52 303±33† ================== Values are means ± SD. Exercise, last 30 min of a 50-minute exercise bout at 50% VO2max, RER, respiratory exchange ratio; FFA, free fatty acid; KIC, alpha-ketolsocaproate; ß-OHB, ß-hydroxybutyrate. * Significantly different from day 1 at P < 0.05. † Significantly different from rest at P < 0.05. KIC isotopic enrichments and leucine kinetics. Steady-state isotopic plateaus in KIC and 13CO2 were reached in both trials during the exercise sampling periods (Fig. 4, A and . Leucine flux did not differ between rest and exercise on day 1. However, 18 days of caloric restriction suppressed leucine flux during exercise relative to both rest on day 18 and exercise on day 1 (Fig. 5A). On days 1 and 18, leucine oxidation more than doubled between rest and exercise (19 vs. 50 µmol·kg–1·h–1). After 18 days of caloric restriction, leucine oxidation was reduced during exercise relative to day 1 exercise values (Fig. 5B). Nonoxidative leucine disposal was attenuated with exercise but was not affected by the caloric restriction (data not shown). Hormone responses during the isotope trials. Insulin concentration was lower during exercise compared with rest on both days 1 and 18, but the fall was greater during exercise on day 18 than on day 1 (Table 2). Exercise induced a significant increase in cortisol concentration during both trials, but there was no impact of dietary energy restriction on the cortisol response during rest or exercise (Table 2). Performance measurements. Performance test results are presented in Table 3. O2 peak did not change over the intervention period when expressed in liters per minute. However, it tended to increase when expressed relative to the declining body weight (ml·kg–1·min–1). Similarly, there was no significant effect of caloric restriction on submaximal endurance time on the cycle ergometer. Subjects experienced a mixed response to caloric restriction on the lift-and-carry vs. arm flexion test with a 12% improvement on the former, but a 20% decrement on the latter. There was a strong association between decrement in arm flexion performance and the quantity of weight lost during the intervention (r = 0.7, P > 0.05; Fig. 6A). When decrement in arm flexion performance was plotted as a function of percent change in body weight, the relationship was maintained with those losing more than 5% of their body weight, demonstrating the greatest reduction in performance (Fig. 6B). The relationship between change in arm flexion and fat-free mass was less robust [r = 0.5, not significant (NS)] and there was little association between improvements in lift-and-carry and change in either body weight or lean mass (r < 0.4, NS). Table 3. Exercise performance data collected during the 21-day intervention ================== Baseline Days 2–3 Days 10–11 Days 20–21 ================== V^O2max l/min 3.5±0.5 3.5±0.5 3.5±0.5 Submax endurance, # min 43.4±21.9 39.9±17.4 Arm flexion, no. of reps 26±6 25±5 26±10 20±8*† Lift and carry, min 5.7±0.7 5.4±0.8 5.2±0.9* 5.0±0.7* =================== Values are means ± SD. # Ride to exhaustion at 70% O2max. Test was performed immediately following the isotope trial of 50 min at 50% of O2max (actually measured on days 1 and 18). * Significantly different from baseline at P < 0.05. † Significantly different from days 2–3 at P < 0.05. .... These data are interpreted to mean that normal-weight individuals have less robust mechanisms to preserve lean mass than obese subjects but can still adapt to 3 wk of moderately severe caloric restriction in a way that minimizes decrements in physical performance. Al Pater, PhD; email: old542000@... __________________________________ - PC Magazine Editors' Choice 2005 http://mail. Quote Link to comment Share on other sites More sharing options...
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