Master Runners Research Articles

Maintenance of BMD in older male runners is independent of changes in training volume or VO(2)peak.

The results of several recent research studies have questioned the benefit of chronic running in reducing the risk of developing osteoporosis. These negative conclusions are based upon the findings that runners, in general, are not different from controls with regard to their bone mineral density (BMD). This has led one to speculate that the value of weight-bearing exercise might be related to its ability to maintain bone mass or, perhaps, decrease the expected rates of loss. We examined a group of 54 male master athletes ranging in age from 40 to 80 years longitudinally over a 5- to 7-year intervening period. Physiological parameters included VO(2)peak, body composition, bone density, and running performance. Medical histories and training records were obtained via questionnaire. Over the average 4.6 years between tests one and two, significant increases in body weight and lean body mass were observed. Aerobic fitness declined, as did weekly mileage and 5K and 10K performance times. Bone mineral density was lower in the whole body but not in the hip or the spine. Finally, we report no significant relationship between the change in training volume, change in body weight or lean mass, and change in aerobic capacity with changes in BMD. Hip and spine BMD are maintained over a 4- to 5-year period in master runners. Furthermore, changes in bone density or content are not sensitive to moderate changes in training volumes. We conclude that bone density can be maintained by running in older active men. These findings suggest that if a minimal threshold of mileage is required, the level is certainly below the average mileage of master runners.

Maximal aerobic power, lactate threshold, and running performance in master athletes.

This study sought to determine how lactate threshold (LT) is related to running performance in older male and female runners, if LT changes significantly with age, and if gender alters the relationship between LT and performance in older runners. Subjects were 168 master runners (111 men, 57 women) selected from a longitudinal study, who ran at least 10 miles x wk(-1) for 5 yr or more. VO2max was measured on a treadmill and body composition by hydrostatic weighing. Blood samples taken each minute of exercise were analyzed for lactate concentration and LT determined as the breakpoint in lactate accumulation. Performance times and training histories were self-reported by questionnaire. Men had significantly greater body mass, fat-free mass (FFM), and VO2max (L x min(-1); mL x kg(-1) x min(-1)) than women. FFM and VO2max (L x min(-1); mL x kg(-1) x min(-1)) declined with age in both men and women. Running performance was significantly different between men and women and declined with age in both. LT (L x min(-1); mL x kg(-1) x min(-1)) was significantly different between men and women, and declined significantly with age in men, whereas LT (%VO2max) did not differ between men and women and increased significantly with age in both. VO2max (mL x kg(-1) x min(-1)) was the most significant predictor of performance in both men and women, whereas LT (L x min(-1)) added to the prediction of 5-km and 10-km performance in women. The results of this study demonstrate that VO2max (mL x kg(-1) x min(-1)) is a better predictor of performance than LT in older male and female runners. Additionally, LT as a percentage of VO2max increases significantly with age.

Heart rate response during incremental exercise in master runners.

We analyzed the kinetics of heart rate (HR) response during incremental treadmill exercise in thirteen master runners (62 +/- 1 yr). The HR/running speed (HR/S) relationship showed the existence of a point of downward deflection (HR(d)) in only approximately 31% of the subjects. Resting echocardiographic evaluations showed similar heart dimensions in all of the subjects. In conclusion, HR does not seem to show a curvilinear response (downward deflection) in most aged athletes.

Short-term effects of marathon running in master runners: no evidence of myocardial injury.

The purpose of this investigation was to analyze the short-term effects of marathon running on serum levels of cardiac markers in a group of master runners (> 60 yrs). Ten marathoners (9 male and 1 female; 63+/-4 yrs) were enrolled in the study. All of them completed the Madrid Marathon (1998). Venous blood was drawn from each subject three times during the study (48 h before the race, immediately after the race, and 24 h post-competition) for the determination of the several biochemical markers, such as total creatine kinase catalytic activity (total CK), mass concentration of creatine kinase isoenzyme MB (CK-MB mass), and cardiac troponin I (Tnl-c). The most important finding was that in each sample (pre- or post-race) serum Tnl-c was below the commonly accepted level of 0.1 ng x m(-1) indicative of myocardial injury. Although further research is needed using more complete methodology, our results suggest that marathon running does not have an acute deleterious effect on the hearts of the elderly.

AGE-RELATED CARDIOVASCULAR RISK FACTOR CHANGES IN MASTERS ATHLETES UTLIZING CROSS-SECTIONAL VS LONGITUDINAL DATA

1940 This study sought to elucidate whether cross-sectional and longitudinal analysis of the influence of chronic exercise on age-related changes in modifiable cardiovascular disease risk factors would provide similar results. Male (N=84, aged 53.38±1.05 years, X±SEM) and female (N=53. aged 48.68±1.08 years) masters runners participated in this study. Baseline measurements were utilized for the cross-sectional analysis, while follow-up measures were obtained at 7.5±0.19 years in the males, and 6.11±0.28 years in the females for the longitudinal analysis. At both time points, fasting plasma was analyzed for glucose (G), triglycerides (T), cholesterol (C), and HDLC. Body composition was determined by hydrodensitometry, and corrected for residual lung volume, while running mileage was obtained from training questionnaires. Genders were subdivided into 3 age groups (40-49, 50-59, and 60± years) for the cross-sectional comparisons. Between and within group differences were determined by ANOVA and paired t-tests, respectively. Longitudinal data are presented in the following table as X±SEM. *Significant longitudinal differences at the p<.05 level.TableLongitudinal analysis of the data suggests significant increases in percent body fat, T, and C, and declines in HDLC and training mileage in both genders (p<.05). However, cross sectional analysis of the data suggests an absence of age group differences for both genders, with the exception of cholesterol, which was significantly higher in the oldest women than in the 40-50 and 50-60 year olds (p=.001 and p=.016, respectively). These results suggest that cross sectional analyses of the effects of chronic exercise during aging on cardiovascular disease risk factors do not accurately reflect longitudinal changes in active older runners. Supported by the R.M. Wadt Research fund.

Isometric force and maximal shortening velocity of single muscle fibers from elite master runners.

Single chemically permeabilized gastrocnemius fibers from six elite endurance-trained master runners (RUN group) and five age-matched sedentary controls (SED group) were mounted between a force transducer and a position motor, studied under conditions of maximal and submaximal Ca2+ activation, and subsequently electrophoresed on 5% polyacrylamide gels to determine myosin heavy chain (MHC) composition. For the SED group, peak isometric tension (Pzero) averaged 143 +/- 3, 156 +/- 4, and 170 +/- 4 kN/m2 and maximal shortening velocity (Vzero) averaged 0.43 +/- 0.01, 1.90 +/- 0.08, and 5.59 +/- 0.40 fiber lengths/s for fibers expressing type I, IIa, and IIx MHC, respectively (all comparisons, P < 0.05). Hill plot analysis of relative forces during submaximal Ca2+ activation indicated no SED vs. RUN differences in Ca2+ sensitivity or in the cooperativity of Ca2+ activation. However, at maximal Ca2+ activation, RUN type I and IIa fibers produced 15% less peak absolute force than SED fibers (P < 0.05). This reduction in fiber force was a direct result of the smaller diameter of the RUN fibers (P < 0.05), because Pzero, peak elastic modulus (Ezero), and Pzero/Ezero were not different between SED and RUN groups. RUN type I fibers also displayed a mean Vzero that was 19% higher than the average Vzero of the SED type I fibers (P < 0.05). In separate experiments, quantification of relative myosin light chain (MLC) isoform content revealed a 28% greater ratio of MLC3 to MLC2 in single type I fibers from the RUN group (P < 0.05), suggesting that the elevated Vzero of the RUN type I fibers was related to a greater expression of MLC3. In conclusion, the single fibers from the elite master runners displayed specific morphological and contractile properties that may enhance the performance of these athletes during prolonged muscular activity.

GEOMETRIC PROPERTIES OF THE PROXIMAL FEMUR IN MASTER RUNNERS 950

The purpose of the study was to examine geometric properties of left proximal femur in 31 male runners and 36 controls (mean ± standard deviation; age = 57 ± 8 vs 55 ± 9 yr, respectively). Maximal oxygen uptake (VO2 max) was measured via indirect calorimetry on a treadmill until volitional exhaustion. Bone mineral density (BMD) was obtained with dual energy x-ray absorptiometry (Lunar DPX*). Runners were significantly (p < 0.05) lighter and shorter (weight = 73 ± 9 vs 78± 9 kg and height = 174 ± 5 vs 177 ± 6 cm) and had a higher VO2 max (48.3 ± 6.6 vs 35.7 ± 6.0 ml·kg-1·min-1) than controls, respectively. Bone mass measurement scans were analyzed with Lunar 1.4C software which yields theoretical estimates of geometric properties for proximal femur,i.e.; cross-sectional area and moment of inertia, tensile and compressive stress (Yoshikawa et al., JBMR, 9, 1994). These properties were used to calculate safety (resistance to fracture for forces generated during walking) and fall (resistance to fracture for forces generated during a fall) factor indices. Runners had significantly (p < 0.05) higher femoral neck BMD (0.954 ± 0.118 vs 0.895 ± 0.113 gcm-2) and greater safety (4.3 ± 0.8 vs 3.7 ± 0.7) and fall (1.3 ± 0.2 vs 1.1 ± 0.2) factor indices than controls, respectively. Controls had significantly (p < 0.05) greater compressive and tensile forces and upper (superior half) BMD in the fermoral neck than runners. Master runners who average more than 20 mi·wk-1 have greater femoral neck BMD and estimated resistance to femoral neck fractures than age-matched controls.

HABITUAL EXERCISE DOES NOT PREVENT THE AGE-ASSOCIATED DECLINE IN GROWTH HORMONE/INSULIN LIKE GROWTH FACTOR-I 25

Human aging is associated with a decline in secretion of growth hormone and insulin like growth factor-I (GH/IGF-I), which has been proposed to contribute to the observed somatic changes in older people. This decline in GH/IGF-I may be due to aging per se or to a reduction in physical activity that also commonly occurs with age. Acute exercise is known to stimulate GH secretion. To determine if habitual exercise prevents or retards age associated changes in GH/IGF-1 status or body composition and muscle strength, we compared 15 masters runners (Active, A) with 15 sedentary men (Non-Active, NA), aged 60 - 70 yrs. Maximal oxygen uptake (VO2 max) assessed by treadmill testing was higher in A than NA (40.0 ± 1.9 vs. 27.3 ± 1.4 ml/kg/min, mean ± SEM, P < 0.001). There was no difference in lean body mass, regional or whole body bone mineral density, but NA had higher (P < 0.05) body weight (73.8 ± 1.8 vs. 84.8 ± 4.0 kg), fat mass (12.8± 0.8 vs. 20.3 ± 2.2 kg) and percent fat (23.2 vs. 17.2) than A as assessed by DXA (Hologic 1000/W). Total IGF-I (A, 129 ± 10 ng/mL vs. NA, 124 ± 11 ng/mL) and the ratio IGF-1:IGFBP3, an index of bioavailable IGF-1 (A, 0.046 vs. NA, 0.048) were similar between goups. Concentric muscle strength (1-RM) for 8 upper and lower body muscle groups was comparable except for knee extension, where A were higher than NA (P < 0.05). With groups combined, there was no relationship between total or bioavailable IGF-I and any body composition or muscle strength variable. Conclusions: These results indicate that even high levels of endurance exercise do not prevent the decline in GH/IGF-I that occurs with normal human aging, and that neither total or bioavailable IGF-I predicts somatic status or muscle strength in healthy older men.

Serum creatine kinase isoenzyme measurements in master male and female marathon runners

This study investigated exercise‐induced muscle enzyme release in master runners by assessing the activity of total serum creatine kinase (total CK) and the concentration of the isoenzyme creatine kinase MB (CK‐MB). Subjects were 12 male (54 ± 9 years) and seven female (50 ± 6 years) master marathon runners. Premarathon (24 hours before) and postmarathon serum samples were collected (24, 48, 72, and 96 hours after the race). Total CK was measured enzymatically and CK‐MB concentration was assayed utilizing a double antibody procedure. The men's and women's 24 hour (1012 U/L, 782 U/L) and 48 hour (581 U/L, 441 U/L) postrace mean total CK activities were significantly (p≤0.05) elevated above prerace values (66 U/L, 119 U/L). CK‐MB concentration 24 hours postrace was also significantly (≤0.05) elevated from prerace values (0.27 ng/ml, 0.0 ng/ml) in both males (34.4 ng/ml) and females (16.7 ng/ml). The results of this study indicate that the pattern of exercise‐induced muscle enzyme release from the stress of ...

Physiological factors associated with the lower maximal oxygen consumption of master runners.

We examined the hemodynamic factors associated with the lower maximal O2 consumption (VO2max) in older formerly elite distance runners. Heart rate and VO2 were measured during submaximal and maximal treadmill exercise in 11 master [66 +/- 8 (SD) yr] and 11 young (32 +/- 5 yr) male runners. Cardiac output was determined using acetylene rebreathing at 30, 50, 70, and 85% VO2max. Maximal cardiac output was estimated using submaximal stroke volume and maximal heart rate. VO2max was 36% lower in master runners (45.0 +/- 6.9 vs. 70.4 +/- 8.0 ml.kg-1.min-1, P less than or equal to 0.05), because of both a lower maximal cardiac output (18.2 +/- 3.5 vs. 25.4 +/- 1.7 l.min-1) and arteriovenous O2 difference (16.6 +/- 1.6 vs. 18.7 +/- 1.4 ml O2.100 ml blood-1, P less than or equal to 0.05). Reduced maximal heart rate (154.4 +/- 17.4 vs. 185 +/- 5.8 beats.min-1) and stroke volume (117.1 +/- 16.1 vs. 137.2 +/- 8.7 ml.beat-1) contributed to the lower cardiac output in the older athletes (P less than or equal 0.05). These data indicate that VO2max is lower in master runners because of a diminished capacity to deliver and extract O2 during exercise.