Endurance Training Group Research Articles

Weekly Strength And Total Exercise Volume Changes During Super-slow, Traditional Strength, And Muscular Endurance Training

PURPOSE The purpose of this study was to investigate the weekly strength and total volume changes that occur during super slow, traditional strength, and muscular endurance training. METHODS Thirty-four healthy adult females (21.1 ± 2.7) were randomly divided into four groups: a control group (C), a traditional strength training group (TS), a traditional muscular endurance training group (TE), and a super-slow strength training group (SS). Subjects trained for 6 weeks, with the first week consisting of two training sessions and the remaining 5 weeks consisting of three training sessions per week. Subjects performed the leg press (LP), squat (SQ), and knee extension (KE). Each training group attended a minimum of 16 out of 17 training sessions in which the LP, SQ, and KE were performed to fatigue for three sets. For each training session, TS lifted a weight with a goal of reaching fatigue in 6–10 repetitions with each repetition lasting 3 seconds (concentric and eccentric); TE lifted a weight with a goal of reaching fatigue in 20–30 repetitions with each repetition lasting 2 seconds (concentric and eccentric); and SS lifted a weight with a goal of producing fatigue within 6–10 repetitions with each repetition lasting 14 seconds (10 seconds concentric, 4 seconds eccentric). Weekly average weight lifted for each exercise within each group (TS, TE, and SS) was calculated. Total exercise volume for all exercises combined was calculated by multiplying the number of sets, weight, repetitions, and time per repetition for all exercises. Repeated measures ANOVA, mixed model with LSD post hoc tests were used for statistical analysis. Level of significance was set at (α=0.05. RESULTS 1) TS strength increased in all exercises each week except LP between weeks 5–6. SS strength increased in SQ each week, LP each week except comparing weeks 4–6, and KE when comparing all weeks, except week 4, to week 6. TE strength increased in SQ when comparing all weeks to weeks 5 and 6, LP when comparing all weeks except week 6, and KE when comparing weeks 2, 3, and 4 to weeks 5 and 6. 2) The percent change in strength between consecutive weeks was similar for all groups with a few exceptions. In KE, TS had a greater change in strength between weeks 1–2 and 2–3 than SS and TE and in LP TS had a greater change in strength between weeks 2–3 than TE. 3) Total volume of exercise was greater in SS than TS and TE each week. CONCLUSIONS TS demonstrated the most consistent gains in weekly strength compared to SS and TE. Although the percent change in strength was generally similar among the three groups, the total volume of exercise was significantly greater in SS compared to TS and TE each week.

Endothelial function in highly endurance-trained and sedentary, healthy young women

Endothelial function is reduced by age, chronic heart failure, coronary artery disease, hypertension or type 2 diabetes, and it is shown that aerobic exercise may reverse this trend. The effect of a high aerobic training status on endothelial function in young, healthy subjects is however less clear. The present study was designed to determine whether endothelial function is improved in highly endurance-trained young women compared to sedentary, healthy controls. Brachial artery diameter was measured in 16 endurance-trained (age: 23.7 +/- 2.5 years, maximal oxygen uptake (VO2max): 60.6 +/- 4.5 ml/kg per min) and 14 sedentary females (age: 23.7 +/- 2.1 years, VO2max: 40.5 +/- 5.6 ml/kg per min) at rest, during flow-mediated dilation (FMD) and after sublingual glycerol trinitrate administration, using high-resolution ultrasound. FMD did not differ between the endurance-trained and the sedentary females (14.8% vs 16.4%, p = NS), despite a substantial difference in VO2max of 50% (p < 0.001). The endurance-trained group possessed however, a 9% larger resting brachial artery diameter when adjusted for body surface area. The results of the present study suggest that endothelial function is well preserved in young, healthy women, and that a high aerobic training status due to long term aerobic training does not improve the dilating capacity any further.

Effect of long-term neck muscle training on pressure pain threshold: A randomized controlled trial

Muscle tenderness has been measured in several studies to evaluate effectiveness of treatment methods, but only short-term results have been reported so far. The aim of the present study was to evaluate the long-term effects of two different muscle training methods on the pressure pain threshold of neck muscles in women with neck pain. Altogether 180 woman with chronic, non-specific neck pain were randomized into three groups: neck muscle endurance training, neck muscle strength training and control groups. The main outcome measures included pressure pain threshold measurement at six muscle sites and on the sternum. Neck pain was assessed by a visual analogue scale (VAS). At the 12-month follow-up statistically significantly higher pressure pain threshold values were obtained in both training groups at all muscle sites compared to the baseline, while no significant change occurred in the controls. Significantly higher changes in pressure pain threshold were detected at all six sites in the strength training group and at four out of six sites in the endurance training group compared to the control group. This is the first study to show an increase in pressure pain thresholds as a result of long-term muscle training. A decrease in neck pain was associated with reduced pressure pain sensitivity in neck muscles, showing that the pressure pain threshold may be a useful outcome measure of the effectiveness of neck muscle rehabilitation.

Cardiovascular autonomic control in endurance‐trained and sedentary young women

This study aimed to investigate whether endurance-trained (ET) female athletes demonstrate differences in cardiovascular autonomic control compared with sedentary controls. Eighteen healthy eumenorrhoeic subjects, nine trained (22.4 +/- 3 years) and nine sedentary (21.0 +/- 1 years), volunteered for the study. Heart rate variability (HRV) and cardiovagal baroreflex sensitivity (BRS) measures were adopted to assess cardiac autonomic control. HRV was recorded for 30 min under both controlled (0.25 Hz) and spontaneous breathing conditions. Cardiovagal BRS was assessed using the Valsalva manoeuvre. Analysis of the HRV showed a longer R-R interval (1089 +/- 114 ms versus 865 +/- 100 ms; P<0.001) in the trained subject but only in the spontaneous breathing condition. Conversely, athletes exhibited higher normalized low frequency (LFnu, 44.2 +/- 8.5% versus 29.5 +/- 6.8%; P<0.001) and lower normalized high frequency (HFnu, 55.8 +/- 8.5% versus 69.9 +/- 7.7%; P<0.01) only during the controlled breathing condition, consequently the LF/HF ratio was also higher in the trained group in the same condition (0.83 +/- 0.3 versus 0.47 +/- 0.1, P<0.01). BRS was significantly lower in the ET group (7.95 +/- 4.0 ms mmHg(-1) versus 13.00 +/- 4.4 ms mmHg(-1), P<0.05). Further studies are necessary to elucidate the potential role of training and altered hormonal profile in the genesis of the observed differences in cardiovascular autonomic control between highly trained and sedentary control female subjects.

Relationships of Anthropometrical Parameters and Body Composition with Bone Mineral Content or Density in Young Women with Different Levels of Physical Activity

The aim of the study was to test the possible relationships of anthropometrical parameters, somatotype and body composition parameters with bone mineral content (BMC) and bone mineral density (BMD, total body, the dominant arm distal radius, antero-posterior lumbar spine--L2-L4, femoral neck) in strength- (n=33) and endurance- (n=32) trained and sedentary normal-weight (n=41) and overweight (n=23) young females. Their body height and mass were measured and BMI calculated. Nine skinfolds, thirteen girths, eight lengths and eight breadths/lengths were measured. Somatotype components were calculated according to Carter and Heath (1990). Whole body fat percentage, fat mass, lean body mass (LBM), BMC and BMD were measured by DXA. The relationship of different BMC and BMD values at each of the regions studied to the different anthropometrical and body composition parameters were analysed by using a stepwise multiple regression analysis. In all groups, BMC is highly dependent on the body mass (31.5-81.2%, R2x100). In the endurance-trained females, BMD is dependent on LBM, especially in both weight-bearing sites (66.2% in L2-L4 and 35.3% in the femoral neck). LBM explained 77.0% of the total variance of BMC in this group. BMC in the strength-trained group is dependent on the lower body anthropometrical parameters--thigh skinfold (18.2%), calf girth (25.2%), trochanterion length (24.1%) and sitting height (51.4%). From the endurance-trained group, BMC is dependent on hip girth (75.2%) or in combination with ankle girth (81.2%). From the length parameters, trochanterion is the most important (55.8%) and from breadths/lengths, sitting height (57.1%). In the normal-weight females, BMC is dependent on the calf girth (31.1%), trochanterion length (28.2%) and sitting height (29.8%). In the overweight group, only chest girth (20.1%) and biacromial breadth/length (27.0%) had a relationship with BMC. From somatotype components, only ectomorphy explained BMD in the endurance-trained females in the femoral neck (21.3%) and in the lumbar spine (20.9%). We can conclude that from the body composition parameters, LBM is a powerful predictor of BMC and BMD. From the anthropometrical parameters measured, lower body parameters are the most important. Somatotype components (ectomorphy) had a relationship with BMD only in the endurance-trained group. There are some differences that depend on the specific physical activity field. In the endurance-trained group, the anthropometry is more important than in the strength-trained group.

Metabolic and vascular support for the role of myoglobin in humans: a multiparametric NMR study

In human muscle the role of myoglobin (Mb) and its relationship to factors such as muscle perfusion and metabolic capacity are not well understood. We utilized nuclear magnetic resonance (NMR) to simultaneously study the Mb concentration ([Mb]), perfusion, and metabolic characteristics in calf muscles of athletes trained long term for either sprint or endurance running after plantar flexion exercise and cuff ischemia. The acquisitions for (1)H assessment of Mb desaturation and concentration, arterial spin labeling measurement of muscle perfusion, and (31)P spectroscopy to monitor high-energy phosphate metabolites were interleaved in a 4-T magnet. The endurance-trained runners had a significantly elevated [Mb] (0.28 +/- 0.06 vs. 0.20 +/- 0.03 mmol/kg). The time constant of creatine rephosphorylation (tauPCr), an indicator of oxidative capacity, was both shorter in the endurance-trained group (34 +/- 6 vs. 64 +/- 20 s) and negatively correlated with [Mb] across all subjects (r = 0.58). The time to reach maximal perfusion after cuff release was also both shorter in the endurance-trained group (306 +/- 74 vs. 560 +/- 240 s) and negatively correlated with [Mb] (r = 0.56). Finally, Mb reoxygenation rate tended to be higher in the endurance-trained group and was positively correlated with tauPCr (r = 0.75). In summary, these NMR data reveal that [Mb] is increased in human muscle with a high oxidative capacity and a highly responsive vasculature, and the rate at which Mb resaturates is well correlated with the rephosphorylation rate of Cr, each of which support a teleological role for Mb in O(2) transport within highly oxidative human skeletal muscle.

Effects of Concurrent Resistance and Aerobic Training on Load-Bearing Performance and the Army Physical Fitness Test

The purpose of this research was to determine the effects of high intensity endurance training (ET) and resistance training (RT) alone and in combination on various military tasks. Thirty-five male soldiers were randomly assigned to one of four training groups: total body resistance training plus endurance training (RT + ET), upper body resistance training plus endurance training [UB + ET), RT only, and ET only. Training was performed 4 days per week for 12 weeks. Testing occurred before and after the 12-week training regimen. All groups significantly improved push-up performance, whereas only the RT + ET group did not improve sit-up performance. The groups that included ET significantly decreased 2-mile run time, however, only RT + ET and UB + ET showed improved loaded 2-mile run time. Leg power increased for groups that included lower body strengthening exercises (RT and RT + ET). Army Physical Fitness Test performance, loaded running, and leg power responded positively to training, however, it appears there is a high degree of specificity when concurrent training regimens are implemented.

Effect of High-Volume and -Intensity Endurance Training in Heart Transplant Recipients

A recommended component of heart transplant recipients (HTR) is endurance-oriented exercise therapy. However, the trainability of HTR after transplantation is vague. We examined the effect of high-volume and -intensity exercise training on exercise performance in HTR, compared with HTR undergoing regular rehabilitation training, and sedentary healthy subjects (SHS). We studied four groups of individuals; of those, three groups were HTR. Subjects were a regularly trained HTR group of denervated (HTR-D; N = 15), reinnervated (HTR-R; N = 26) hearts, a high-volume and -intensity endurance-training group (training time 7-20 h.wk(-1); HTR-ET; N = 12), and a group of sedentary healthy subjects (SHS; N = 21). All participants performed cardiopulmonary exercise testing. The HTR-ET achieved a significantly higher performance (255 +/- 47 W, VO(2max) of 45.2 +/- 6.9 mL.kg(-1).min(-1)) in contrast to all other groups (HTR-D: 119 +/- 17 W, VO(2max) of 17.4 +/- 4.5 mL.kg(-1).min(-1); HTR-R: 119 +/- 17 W, VO(2max) of 16.9 +/- 3.7 mL.kg(-1).min(-1); SHS: 184 +/- 19 W, VO(2max) of 35.0 +/- 6.9 mL.kg(-1).min(-1)). The HR at maximal power output in the HTR-ET was 169 +/- 17 bpm and similar to SHS (164 +/- 17 bpm), but significantly higher than HTR-D (125 +/- 16) and HTR-R (142 +/- 10). Maximal lactate concentration (LAmax) of HTR-ET was 9.9 +/- 2.2 mmol.L(-1), comparable to SHS (9.2 +/- 2.1 mmol.L(-1)), and significantly higher than HTR-D (5.5 +/- 1.5 mmol.L(-1)) and HTR-R (5.1 +/- 1.0 mmol.L(-1)). Data suggest that HTR can perform high-volume and -intensity exercise training, reaching exercise performance comparable to or even exceeding values of sedentary or moderately trained healthy subjects.

Composition and turnover of contractile proteins in volume-overtrained skeletal muscle.

The purpose of this study was to find the composition shift of myosin heavy chain (MyHC) isoforms in overtraining in fast- and slow-twitch skeletal muscles and different changes in MyHC isofom composition, synthesis and turnover rate between 4-week and 6-week overtraining. Male Wistar rats were randomly assigned to 4-week and 6-week endurance training, 4-week and 6-week overtraining groups. Plantaris (Pla), extensor digitorum longus (EDL), and soleus (Sol) muscles were studied. Daily excretion of 3-methylhistidine (3-MeHis) pool as an indicator for protein degradation increased in the 4-week and 6-week overtraining group to 4.04 +/- 0.21 and 4.32 +/- 0.23 %/day subsequently in comparison with the control group (2.16 +/- 14 %/day, p < 0.001). In Pla muscle MyHC I isoform synthesis rate was 33 200 +/- 2150 (after 6-week overtraining 27 100 +/- 1800, p < 0.05), IIa 32 600 +/- 2100; IId 27 300 +/- 1890 and IIb isoform 20 100 +/- 1600 (after 6-week overtraining 15 500 +/- 1400, p < 0.05) dpm/M leucine/min. Actin synthesis rate increased in fast-twitch muscles during 4- and 6-week overtraining, and in soleus muscle during 6-week overtraining. In EDL and Sol muscle MyHC isoform composition during 6-week overtraining did not change significantly. During the 6-week overtraining the relative content of MyHC I and IIb isoforms decreased and IIa and IId isoforms increased in Pla muscle. The initial increase of MyHC IIb isoform after 4-week overtraining shows the higher stability of this isoform in comparison with MyHC I isoform in fast-twitch muscles during high volume exercise.

Endurance and Strength Training in Patients With COPD

The purpose of this study was to compare the effects of endurance training only to endurance plus strength (combined) training in a randomized trial of patients with COPD. Twenty-four patients completed the study: 11 patients in the combined training group (FEV(1) 45 +/- 5% predicted), and 13 patients in the endurance training group (FEV(1) 40 +/- 4% predicted) [mean +/- SE]. Muscle strength, quality of life, exercise performance, and quadriceps fatigability were measured before and after rehabilitation. Combined training led to significant improvements in quadriceps (23.6%), hamstring (26.7), pectoralis major (17.5%), and latissimus dorsi (20%) muscle strength. Endurance training alone did not produce significant improvements in muscle strength: quadriceps (1.1% decrease), hamstring (12.2% increase), pectoralis major (7.8% increase), and latissimus dorsi (2.8% decrease). The increase in strength after training was significantly greater in the combined group compared to the endurance group for the quadriceps and latissimus dorsi muscles but not for the hamstring and pectoralis major muscles. Six-minute walk distance, endurance exercise time, and quality of life (as measured by the Chronic Respiratory Questionnaire) significantly increased in both groups after rehabilitation with no significant differences in the extent of improvement between groups. The extent of improvement in quadriceps fatigability after training (assessed by quadriceps twitch force before and after exercise) was not significantly different between groups. Strength training can lead to significant improvement in muscle strength in elderly patients with COPD. However, this improvement in muscle strength does not translate into additional improvement in quality of life, exercise performance or quadriceps fatigability compared to that achieved by endurance exercise alone.

The Effects of Resistance, Endurance, and Concurrent Training on Performance Variables in Previously Untrained Men

0397 The specificity of training principle predicts that combining resistance and endurance training could interfere with the maximum development of strength and endurance capacity that results from either type of training alone. PURPOSE: To determine if endurance training and resistance training performed concurrently produces different performance and physiologic results compared to each type of training alone. METHODS: 45 untrained men were recruited and random1y assigned to one of three training groups; endurance training (ET), resistance training (RT), and concurrent training (CT). All groups were tested for the following variables prior to and after 12 weeks of training: percent (%) body fat, peak oxygen consumption (VO2peak), isokinetic peak torque and average power produced during single-leg flexion and extension at 60 and 180 deg/sec, 1 repetition maximum (1 RM) leg press, 1 RM bench press, vertical jump height, calculated jump power, and 40-yard dash time. RESULTS: Body weight increased significantly (P < 0.05) in the RT and CT groups; % body fat was significantly decreased in the ET and CT groups. VO2peak was significantly improved (+8.24%) only in the ET group. Peak torque during flexion and extension at 180 deg/sec was improved 10–11% in the RT group. In the ET, RT, and CT groups 1 RM improvements in leg press (20.4%, 40.8%, and 39.4%, respectively) and bench press (7.5%, 30.5%, and 21.2%, respectively) were significant. RT and CT 1 RM improvements were not significantly different, but greater than those of the ET group. Jump power improved significantly only in the RT group. No group showed a significant change in vertical jump height or 40-yard dash time. CONCLUSIONS: Our findings show that concurrent training does not interfere with strength development, but may hinder development of maximal aerobic capacity.

Effects of Endurance Training on Adenosine A2A Receptor Density in Myocardium and Skeletal Muscle

0182 Adenosine is an endogenous modulator of several physiological functions in the central nervous system as well as peripheral organs such as myocardium and skeletal muscle. The effects are mediated by at least four subtypes: A1, A2A, A2B, and A3 receptors. In particular, adenosine A2A receptor is involved in myocardial contractility and glucose utilization in the skeletal muscle. PURPOSE: The primary aim of the present study is to evaluate adenosine A2A receptors in the myocardium and skeletal muscle in humans with positron emission tomography (PET) and [7-methyl-11C]-(E)-8-(3,4,5-trimethoxystyryl)-1,3,7-trimethylxanthine ([11C]TMSX), a potential radioligand for mapping adenosine A2A receptors. Second goal is to investigate the effects of endurance training on the densities of adenosine A2A receptors in myocardial and skeletal muscle. METHODS: Four untrained (24±2 yrs) and three endurance-trained subjects (triathlete, 22±2 yrs) participated in this study. The values of peak oxygen uptake were measured during both cycling and arm-cranking exercise. The density of adenosine A2A receptors was evaluated as the distribution volume of [11C]TMSX in the left ventricular myocardium and upper limb muscle (triceps brachii) in the resting state with PET. RESULTS: The peak oxygen uptake was significantly higher in the trained subjects than in the untrained subjects (cycling: 68±3 vs. 47±8 mL/kg/min, p<0.05; armcranking: 38±2 vs. 31±4 mL/kg/min, p<0.05). The distribution volume of [11C]TMSX in the myocardium was much larger than that in the upper limb muscle (3.0±0.4 vs. 0.5±0.2 g/mL, p<0.05). The distribution volumes in the myocardium were not different between in the untrained and endurance-trained groups (2.8±0.3 vs. 3.3±0.5 g/mL, respectively, p = 0.15). In contrast, the densities of adenosine A2A receptors in the upper limb muscle were significantly different between the two groups: the distribution volume in the endurance-trained group was significantly higher than that in the untrained group (0.4±0.1 vs. 0.8±0.1 g/mL, p<0.05). CONCLUSION: These results indicate that the density of adenosine A2A receptors in the myocardium was much highly than that in skeletal muscle, and that endurance training may increase the density of adenosine A2A receptors in the skeletal muscle, but not in the myocardium.

The Physiological Effects of Two Modes of Endurance Training In Persons With SCI

2090 Introduction: Arm ergometry (AE) and wheelchair propulsion are the two primary modes of exercise training available to individuals with spinal cord injury (SCI). The physiological adaptations to exercise training using upper extremity press/pull (UEPP) motions have not been extensively investigated. PURPOSE: The purpose of this study was to compare the physiological adaptations to reciprocal UEPP training with AE training in chronic survivors of SCI. Methods: Ten subjects (8 males and 2 females, 5 paraplegics and 3 quadriplegics) participated in this study (38.0» 12.3 yrs. and 79.0» 22.2 kg). Subjects were assigned to one of two endurance-training groups, either AE endurance training or reciprocal UEPP endurance training. Both groups trained 3 days/wk over an 8-wk study period. The training intensity for both groups was 70 – 85% peak heart rate. All subjects participated in peak AE testing, arm Wingate Anaerobic Testing (WAnT), and isokinetic strength testing prior to and following the training period. The peak AE tests were performed using a discontinuous protocol on a Monark arm ergometer. Metabolic responses and heart rate were continuously monitored via open-circuit spirometry and 12-lead EKG. The initial stage was performed without resistance at 50 rpm for three min. Subsequent stages progressed with increases of 10W/stage. WAnT was performed on a Monark 834 ergometer mounted to an adjustable table with resistance applied to the flywheel equivalent to 3.5% of the subjects' body mass. Isokinetic strength was determined for shoulder and elbow flexion and extension with velocity fixed at 60 degrees/sec. Results: Peak VO2 significantly increased 14% and 15% for UEPP and AE, respectively, with no significant differences detected between groups. Mean WAnT power increased significantly in the UEPP group (105 W to 111 W (P< 0.05) with no statistically significant training effects detected in the AE group. Elbow extension and shoulder flexion force significantly increased in the UEPP group with no significant differences between groups. Conclusion: Chronic survivors of SCI can significantly improve their upper extremity cardiorespiratory endurance, muscular strength, and muscular power by undergoing a short-term reciprocal UEPP training program.

Effects of Chronic Aerobic Exercise on Skeletal Muscle Uncoupling Protein 3

1257 Skeletal muscle uncoupling protein 3 (UCP3) is thought to uncouple oxidative phosphorylation from ATP production and therefore contribute to whole body energy metabolism. UCP3 may also have a role in the pathophysiology of obesity. It has been hypothesized that the increase in energy efficiency associated with endurance training is a result of decreased skeletal muscle UCP3. However, we have recently demonstrated that endurance training does not down regulate UCP3 mRNA. Although we did not expect changes in UCP3 protein levels it is possible that UCP3 could be regulated post-transcriptionally by endurance training. There is a lack of data that addresses the effects of exercise training on UCP3 protein levels. PURPOSE: To determine the chronic effects of aerobic exercise on basal UCP3 protein levels in endurance trained rats. METHODS: Fifteen Sprague Dawley rats were randomly assigned to control (C, n = 8) or endurance training (T, n = 7) groups. T rats trained five days weekly for a period of eight weeks on a motorized treadmill. T rats ran at 28 m/min for approximately 60 minutes per day. All rats were sacrificed 48 hours after the final training session. The soleus muscle was rapidly removed, frozen in liquid nitrogen and stored at −80° C until analysis. UCP3 levels were estimated by western blots and the optical density and area of the resultant bands was determined. Citrate synthase activity (CS) was also determined and used as a measure of aerobic conditioning. RESULTS: CS activity (nmol/mg prot./min) was significantly higher (P = 0.027) after training in the soleus muscle of T versus C. Basal UCP3 protein levels did not differ (P = 0.8) between T and C animals in the soleus muscle. CONCLUSIONS: These data suggest that eight weeks of treadmill running in rats which produced a significant aerobic training effect as measured by CS activity does not down regulate the basal protein levels of UCP3 at least in the predominantly slow twitch soleus muscle.

Control of maximum metabolic rate in humans: dependence on performance phenotypes.

Borrowing from metabolic control analysis the concept of control coefficients or ci values, defined as fractional change in MMR/fractional change in the capacity of any given step in ATP turnover, we used four performance phenotypes to compare mechanisms of control of aerobic maximum metabolic rate (MMR): (i) untrained sedentary (US) subjects, as a reference group against which to compare (ii) power trained (PT), (iii) endurance trained (ET), and (iv) high altitude adapted native (HA) subject groups. Sprinters represented the PT group; long distance runners illustrated the ET group; and Andean natives represented the HA group. Numerous recent studies have identified contributors to control on both the adenosine triphosphate (ATP) supply side and the ATP demand side of ATP turnover. From the best available evidence it appears that at MMR all five of the major steps in energy delivery (namely, ventilation, pulmonary diffusion, cardiac output, tissue capillary--mitochondrial O2 transfer, and aerobic cell metabolism per se) approach an upper functional ceiling, with control strength being distributed amongst the various O2 flux steps. On the energy demand side, the situation is somewhat simplified since at MMR approximately 90% of O2-based ATP synthesis is used for actomyosin (AM) and Ca2+ ATPases; at MMR these two ATP demand rates also appear to be near an upper functional ceiling. In consequence, at MMR the control contributions or ci values are distributed amongst all seven major steps in ATP supply and ATP demand pathways right to the point of fatigue. Relative to US (the reference group), in PT subjects at MMR control strength shifts towards O2 delivery steps (ventilation, pulmonary diffusion, and cardiac output); here physiological regulation clearly dominates MMR control. In contrast in ET and HA subjects at MMR control shifts towards the energy demand steps (AM and Ca2+ ATPases), and more control strength is focussed on tissue level ATP supply and ATP demand. One obvious advantage of the ET and HA biochemical-level control is improved metabolite homeostasis. Additionally, with some reserve capacity in the O2 delivery steps, the focussing of control on ATP turnover at the tissue level has allowed nature to improve on an 'endurance machine' design.

EFFECTS OF RESISTANCE VERSUS ENDURANCE TRAINING ON CARDIORESPIRATORY AND MUSCULAR FITNESS IN PERSONS WITH PARAPLEGIA

Purpose This study compared the effects of a structured 12-wk resistance training program with 12-wks of endurance training on peak VO2, upper extremity strength and power output in persons with chronic paraplegia. Methods Sixteen subjects, (29.8 ± 8.1 yrs and 72.9 ± 20.0 kg), with neurologically complete paraplegia at the T6-10 levels, participated in this study. Subjects were matched into pairs (gender and body mass) and assigned to one of two training groups. One group completed 12-wks of upper extremity resistance training (RT) 3 days/wk. Six bilateral resistance maneuvers were performed: chest press, horizontal row, shoulder press, high pull, dips, and bicep curls. Subjects performed three sets of 10 repetitions on each exercise at 70% of one repetition maximum (1RM). Upper extremity strength (1RM) was assessed prior to training and every four wks thereafter using the Mayhew regression equation. The endurance training (ET) group performed 30 min of arm ergometry at 70–85% of HRpeak 3 days/wk for 12-wks. Peak VO2 was determined using a discontinuous protocol on a Monark arm ergometer. Metabolic responses and heart rate were continuously monitored via open-circuit spirometry and 12-lead EKG. Power output was increased 10W/stage to the point of volitional exhaustion. Pre- and post-training arm Wingate Anaerobic Tests (WAnT) were performed using a resistance level equivalent to 3.5% of the subjects' body mass. Outcome variables were compared between groups and across time using two-way ANOVA for repeated measures. Results Following training, peak VO2 significantly increased (p < 0.05) for both groups 15.5 to 17.2 ml*kg−1*min−1 (RT) and 16.5 to 18.5 ml*kg−1*min−1 (ET), with no significant differences observed between groups. Upper extremity strength and peak power significantly increased in the RT (p < 0.01), with no significant changes observed in the ET group. Conclusion The findings of this study indicate that chronic survivors of paraplegia can significantly improve their cardiorespiratory endurance, upper extremity strength, and power output through the participation in a short-term resistance training program.

Decline in insulin action with age in endurance-trained humans.

We tested the hypothesis that regular endurance exercise prevents the age-related decline in insulin action typically observed in healthy, sedentary adults. An index of whole body insulin sensitivity (ISI), obtained from minimal model analysis of insulin and glucose concentrations during a frequently sampled intravenous glucose tolerance test, was determined in 126 healthy adults: 25 young [27 +/- 1 (SE) yr; 13 men/12 women] and 43 older (59 +/- 1 yr; 20/13) sedentary and 25 young (29 +/- 1 yr; 12/13) and 33 older (60 +/- 1 yr; 20/13) endurance trained. ISI values were lower in the older vs. young adults in both sedentary (-53%; 3.9 +/- 0.3 vs. 7.0 +/- 0.7 x10(-4) x min(-1) x microU(-1) x ml(-1); P < 0.01) and endurance-trained (-36%; 7.9 +/- 0.6 vs. 12.4 +/- 1.0 x 10(-4) min(-1) x microU(-1) x ml(-1); P < 0.01) groups, but the value was 72-102% higher in the trained subjects at either age (P < 0.01). In subgroup analysis of sedentary and endurance-trained adults with similar body fat levels (n = 62), the age-related reduction in ISI persisted only in the endurance-trained subjects (12.9 +/- 1.9 vs. 8.7 +/- 1.2 x 10(-4) x min(-1) x microU(-1) x ml(-1); P < 0.01). The results of the present study suggest that habitual endurance exercise does not prevent the age-associated decline insulin action. Moreover, the age-related reduction in ISI in endurance-trained adults appears to be independent of adiposity.

Clinical evaluation of the ACS:180 cardiac troponin I assay

All patients admitted to the coronary care unit with suspected acute coronary syndromes were evaluated by serial electrocardiography and blood draws on admission and at 4 and 12h from admission. Diagnosis was based on conventional WHO criteria. Samples were measured for creatine kinase (CK), cardiac troponin T (cTnT), myoglobin, CK isoenzyme MB (CK-MB) and cardiac troponin I (cTnI). A set of samples from individuals undergoing extreme endurance training was also examined. Analytical imprecision was consistent with published quality goals. Samples were stable for cTnI under a range of storage conditions, including multiple freeze-thaw cycles. CK-MB, cTnI and cTnT were equally efficient for the diagnosis of acute myocardial infarction, irrespective of the final diagnostic criteria used. Both cTnI and cTnT were of equal efficiency in the identification of a high-risk subgroup of patients with unstable angina. Significant elevations of cTnI were not seen in an endurance-training group.

Effects of endurance training on resting and post-exercise cardiac autonomic control.

Endurance training induces reductions in both resting and postexercise heart rate (HR). If adaptation in cardiac autonomic regulation is a contributing factor in these reductions, changes in cardiac autonomic nervous system (ANS) should correspond to those in HR during an endurance-training program. We investigated the changes in resting and postexercise HR variabilities (both in the time and frequency domain) over a 6-wk training program. HR variability was measured five times in an endurance-training group (N = 7) and four times in a control group (N = 5) during the course of study. Endurance training decreased HR and increased indices of parasympathetic modulation measured both at rest and during postexercise recovery periods. Noteworthy is that no changes in either HR or indices of ANS modulation measured during postexercise recovery periods were detectable after the first 7 d of the study despite continued changes in resting HR and indices in ANS modulation measured between the 7th and 42nd days of the endurance-training program. The study demonstrates that with endurance-training changes in cardiac ANS modulation partly contribute to a decrease in HR at rest and during postexercise recovery period, and that adaptation of the cardiac autonomic control occurs sooner in immediate postexercise periods than at rest.

EFFECTS ON PHYSICAL PERFORMANCE AND PAIN FROM THREE DYNAMIC TRAINING PROGRAMS FOR WOMEN WITH WORK-RELATED TRAPEZIUS MYALGIA

To compare training programs for women with trapezius myalgia regarding physical performance and pain, 102 women were randomized to strength, endurance, co-ordination and non-training groups. Before and after the intervention, static strength and dynamic muscular endurance in shoulder muscles were measured on a Cybex II dynamometer. Muscle activity in shoulder muscles was monitored via surface EMG. The signal amplitude ratio between the active and passive phase of repeated contractions indicated the ability to relax. Pain at present, pain in general and pain at worst were measured on visual analogue scales. After training, within group comparisons showed that the training groups rated less pain, and in the strength training group ratings of pain at worst differed from the non-training group. Using the non-training group as a reference, static strength increased in the strength and endurance training groups and muscular endurance in all training groups. The study indicates that regular exercises with strength, endurance or co-ordination training of neck/shoulder muscles might alleviate pain for women with work-related trapezius myalgia.