Effects of intra-session concurrent endurance and strength training sequence on aerobic performance and capacity

Aim: To examine the effects of the sequencing order of individualised intermittent endurance training combined with muscular strengthening on aerobic performance and capacity. Methods: Forty eight male sport students (mean (SD) age 21.4 (1.3) years) were divided into five homogeneous groups according to their maximal aerobic speeds (vV^·O₂MAX). Four groups participated in various training programmes for 12 weeks (two sessions a week) as follows: E (n = 10), running endurance training; S (n = 9), strength circuit training; E+S (n = 10) and S+E (n = 10) combined the two programmes in a different order during the same training session. Group C (n = 9) served as a control. All the subjects were evaluated before (T0) and after (T1) the training period using four tests: (1) a 4 km time trial running test; (2) an incremental track test to estimate vV^·O₂MAX; (3) a time to exhaustion test (t_lim) at 100% vV^·O₂MAX; (4) a maximal cycling laboratory test to assess V^·O₂MAX. Results: Training produced significant improvements in performance and aerobic capacity in the 4 km time trial with interaction effect (p<0.001). The improvements were significantly higher for the E+S group than for the E, S+E, and S groups: 8.6%, 5.7%, 4.7%, and 2.5% for the 4 km test (p<0.05); 10.4%, 8.3%, 8.2%, and 1.6% for vV^·O₂MAX (p<0.01); 13.7%, 10.1%, 11.0%, and 6.4% for V^·O₂MAX (ml/kg^0.75/min) (p<0.05) respectively. Similar significant results were observed for t_lim and the second ventilatory threshold (%V^·O₂MAX). Conclusions: Circuit training immediately after individualised endurance training in the same session (E+S) produced greater improvement in the 4 km time trial and aerobic capacity than the opposite order or each of the training programmes performed separately.     

The effect of pure aerobic training on aerobic and anaerobic capacity.

Twenty men (Group I) and twenty-seven men (group II) took part in a 3-week training course. The training was aerobic and consisted of marching and hiking. The intensity of the training regimen in Group II was greater than for Group I. The maximal oxygen uptake (VO2 max) increased significantly in both groups, more in Group II than in Group I, though no significant change was found in anaerobic capacity. It can be concluded that aerobic training cannot induce improvement in anaerobic capacity.     

Strength training improves muscle aerobic capacity and glucose tolerance in elderly

The primary aim of this study was to investigate the effect of short‐term resistance training (RET) on mitochondrial protein content and glucose tolerance in elderly. Elderly women and men (age 71 ± 1, mean ± SEM) were assigned to a group performing 8 weeks of resistance training (RET, n = 12) or no training (CON, n = 9). The RET group increased in (i) knee extensor strength (concentric +11 ± 3%, eccentric +8 ± 3% and static +12 ± 3%), (ii) initial (0–30 ms) rate of force development (+52 ± 26%) and (iii) contents of proteins related to signaling of muscle protein synthesis (Akt +69 ± 20 and mammalian target of rapamycin +69 ± 32%). Muscle fiber type composition changed to a more oxidative profile in RET with increased amount of type IIa fibers (+26.9 ± 6.8%) and a trend for decreased amount of type IIx fibers (?16.4 ± 18.2%, P = 0.068). Mitochondrial proteins (OXPHOS complex II, IV, and citrate synthase) increased in RET by +30 ± 11%, +99 ± 31% and +29 ± 8%, respectively. RET resulted in improved oral glucose tolerance measured as reduced area under curve for glucose (?21 ± 26%) and reduced plasma glucose 2 h post‐glucose intake (?14 ± 5%). In CON parameters were unchanged or impaired. In conclusion, short‐term resistance training in elderly not only improves muscular strength, but results in robust increases in several parameters related to muscle aerobic capacity.     

Maximal strength training improves aerobic endurance performance

The aim of this experiment was to examine the effects of maximal strength training with emphasis on neural adaptations on strength- and endurance-performance for endurance trained athletes. Nineteen male cross-country skiers about 19.7 +/- 4.0 years of age and a maximal oxygen uptake (VO(2 max)) of 69.4 +/- 2.2 mL x kg(-1) x min(-1) were randomly assigned to a training group (n = 9) or a control group (n = 10). Strength training was performed, three times a week for 8 weeks, using a cable pulley simulating the movements in double poling in cross-country skiing, and consisted of three sets of six repetitions at a workload of 85% of one repetition maximum emphasizing maximal mobilization of force in the concentric movement. One repetition maximum improved significantly from 40.3 +/- 4.5 to 44.3 +/- 4.9 kg. Time to peak force (TPF) was reduced by 50 and 60% on two different submaximal workloads. Endurance performance measured as time to exhaustion (TTE) on a double poling ski ergometer at maximum aerobic velocity, improved from 6.49 to 10.18 min; 20.5% over the control group. Work economy changed significantly from 1.02 +/- 0.14 to 0.74 +/- 0.10 mL x kg(-0.67) x min(-1). Maximal strength training with emphasis on neural adaptations improves strength, particularly rate of force development, and improves aerobic endurance performance by improved work economy.     

Adding strength to endurance training does not enhance aerobic capacity in cyclists

The molecular signaling of mitochondrial biogenesis is enhanced when resistance exercise is added to a bout of endurance exercise. The purpose of the present study was to examine if this mode of concurrent training translates into increased mitochondrial content and improved endurance performance. Moderately trained cyclists performed 8 weeks (two sessions per week) of endurance training only (E, n = 10; 60‐min cycling) or endurance training followed by strength training (ES, n = 9; 60‐min cycling + leg press). Muscle biopsies were obtained before and after the training period and analyzed for enzyme activities and protein content. Only the ES group increased in leg strength (+19%, P < 0.01), sprint peak power (+5%, P < 0.05), and short‐term endurance (+9%, P < 0.01). In contrast, only the E group increased in muscle citrate synthase activity (+11%, P = 0.06), lactate threshold intensity (+3%, P < 0.05), and long‐term endurance performance (+4%, P < 0.05). Content of mitochondrial proteins and cycling economy was not affected by training. Contrary to our hypothesis, the results demonstrate that concurrent training does not enhance muscle aerobic capacity and endurance performance in cyclists.     

Training high--living low: changes of aerobic performance and muscle structure with training at simulated altitude.

This study was undertaken to test the hypothesis that endurance training in hypoxia is superior to training of the same intensity in normoxia. To avoid adaptation to hypoxia, the subjects lived under normoxic conditions when not training. A secondary objective of this study was to compare the effect of high- vs. moderate-intensity training on aerobic performance variables. Thirty-three men without prior endurance training underwent a cycle ergometer training of 6 weeks, 5 d/week, 30 minutes/d. The subjects were assigned to 4 groups, N-high, N-low, H-high and H-low based on the training criteria normoxia (N; corresponding to a training altitude of 600 m), vs. hypoxia (H; training altitude 3850 m) and intensity (high; corresponding to 80% and low: corresponding to 67% of VO2max). VO2max measured in normoxia increased between 8.5 to 11.1%, independent of training altitude or intensity. VO2max measured in hypoxia increased between 2.9 and 7.2%. Hypoxia training resulted in significantly larger increases than normoxia training. Maximal power that subjects could maintain over a thirty-minute period (measured in normoxia or hypoxia) increased from 12.3 - 26.8% independent of training altitude. However, subjects training at high intensity increased performance more than subjects training at a low intensity. Muscle volume of the knee-extensors as measured by magnetic resonance imaging increased significantly in the H-high group only (+ 5.0%). Mitochondrial volume density measured by EM-morphometry in biopsy samples of m. vastus lat. increased significantly in all groups with the highest increase seen in the H-high group (+ 59%). Capillary length density increased significantly in the H-high group only (+ 17.2%). The main finding of this study is that in previously untrained people, training in hypoxia while living at low altitude increases performance in normoxia to the same extent as training in normoxia, but leads to larger increases of aerobic performance variables when measured under hypoxic conditions. Training intensity had no effect on the gain of VO2max. On the level of skeletal muscle tissue, the combination of hypoxia with high training intensity constitutes the most effective stimulus for increasing muscle oxidative capacity.     

Evaluation of smoking interventions in recruit training

Smoking prevention and cessation programs were implemented and evaluated in recruit training. Four groups of incoming recruits were compared: an education group, a no-smoking group, a health risk appraisal feedback group, and a no-treatment control group. Smoking behavior, perceptions related to smoking, and knowledge about smoking were assessed. Recruits in the education and no-smoking groups were less likely to start smoking for the first time during recruit training than recruits in the control group. The education group had fewer smokers stop smoking than the control group. The 2-year follow-up evaluation needs to be conducted before the long-term effects of these programs on prevention and cessation of smoking can be determined.     

Effects of high- and low-intensity exercise training on aerobic capacity and blood lipids

Sixteen non-obese, non-smoking males, ages 20-30 yr, were assigned to one of two training groups, exercising on a cycle ergometer 3 d/wk for 18 wk: high-intensity (H; N = 7; 80-85% Vo2max, 25 min/session) or low-intensity (L; N = 9; 45% VO2max, 50/min/session). Data were obtained at 3-wk intervals for Vo2max, body weight, percent body fat, and 12-h fasting blood levels of cholesterol (CHOL), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C). The average post-training increase in VO2max for group H (0.56 l X min-1, 8.5 ml X min-1 X kg-1) was not significantly (P greater than 0.05) greater than for group L (0.45 l X min-1, 6.5 ml X min-1 X kg-1). Significant reductions in percent body fat occurred in both groups, amounting to an average fat loss of approximately 1.35 kg. No statistically significant changes in CHOL, TG, HDL-C, LDL-C, CHOL/HDL-C, or HDL-C/LDL-C occurred in either group. However, changes in HDL-C after 18 wk of training were inversely correlated (r = -0.57, P less than 0.05) with pre-training levels. We conclude that 1) the minimum exercise training-intensity threshold for improving aerobic capacity is at least 45% Vo2max; 2) 18 wk of high- or low-intensity exercise training is ineffective in significantly altering CHOL, TG, HDL-C, LDL-C, CHOL/HDL-C, and HDL-C/LDL-C in young male subjects with low blood lipid levels, and 3) exercise training-induced changes in HDL-C are dependent upon initial pre-training levels.     

The 5 and 15 minute runs as predictors of aerobic capacity in high school students

Many coaches use field tests to estimate athlete's aerobic capacity. Recently it has been has suggested that the 5 minute run an accurate estimator of aerobic capacity as is the 15 minute aerobic run. The aim of this experiment was to determine whether the 5 minute run was as accurate an indicator of aerobic capacity as the 15 minute run. Also we wished to determine some correlational values between measured VO2max and both the 15 minute and 5 minute runs as well as determining some regression equations to calculate VO2max (mls.kg-1.min-1) given the distance run in the 5 or 15 minute runs. We found that the 15 minute run was still the best indicator of aerobic capacity for all age groups (r = 0.881, 851, 671 and 881 for 12, 13, 14, and 15 years respectively). The 5 minute run correlated significantly with the 15 minute run and with VO2max, in all cases. Correlational values were all moderate to high in nature with no correlation being lower than r = 0.534. We would conclude that the best method to estimate aerobic capacity in a field situation is to use the 15 minute run.     

Muscle performance,sex hormones and training in peri-menopausal and post-menopausal women

Age-related deterioration in muscle performance is one of the major reasons for decreased functional capacity and disability in older people. In women, impaired muscle performance has already been observed during peri-menopause in concert with rapid and dramatic decrease in ovarian hormone production. This observation suggests that female sex steroids may have an important role among other agents in regulating muscle performance in middle-aged and older women. Previous experimental studies have shown that hormone replacement therapy (HRT) and intensive physical training have positive effects on muscle force and explosive power in healthy post-menopausal women. Hormone replacement therapy in combination with physical training may exert even greater gains in muscle performance than HRT and training alone. Despite the significant mean increase in muscle force and power by HRT and/or training, a considerable variability in the individual responses is observed. The mechanism, by which female sex steroids act on muscle performance, is still unclear. Therefore, more research is needed in order to explore all the pathways, by which these steroids could act on skeletal muscle in peri-menopausal and post-menopausal women.     

Improving aerobic power in primary school boys: a comparison of continuous and interval training

The purpose of this study was to assess whether the magnitude of change in aerobic power was different in boys (mean age 10.25 +/- 0.50 y) who followed a high-intensity interval training protocol, compared to those who followed a moderate-intensity continuous training protocol. Boys were assigned to either a control group (n = 15), a continuous training group (n = 10), or an interval training group (n = 10). They completed peak oxygen uptake tests at baseline and following an 8-week training period. The control group continued with normal activity habits, whilst the continuous training group followed a 20-minute steady-state cycle protocol at 80-85 % of the maximal heart rate, and the interval training group completed 30-s sprints on a cycle ergometer, interspersed with active rest periods. The two training protocols were designed to incur similar cardiovascular work over the 20 minutes of each training session. Significant increases (p < 0.05) in peak oxygen uptake were noted for both the interval and continuous training groups. The interval training group showed marked pre- to post-increases in both peak oxygen pulse, oxygen pulse at the ventilatory threshold, and ventilatory threshold that were not apparent in the continuous group boys. It would appear that a high-intensity interval protocol confers a different training effect in comparison to continuous steady-state training in boys. Possible mechanisms that underpin these adaptations may include increased blood volume and a concomitant adjustment in stroke volume.     

Physiological and performance effects of generic versus specific aerobic training in soccer players

The aim of this study was to compare the effects of specific (small-sided games) vs. generic (running) aerobic interval training on physical fitness and objective measures of match performance in soccer. Forty junior players were randomly assigned to either generic (n=20) or specific (n=20) interval training consisting of 4 bouts of 4 min at 90-95 % of maximum heart rate with 3 min active rest periods, completed twice a week. The following outcomes were measured at baseline (Pre), after 4 weeks of pre-season training (Mid), and after a further 8 weeks of training during the regular season (Post): maximum oxygen uptake, lactate threshold (Tlac), running economy at Tlac, a soccer-specific endurance test (Ekblom's circuit), and indices of physical performance during soccer matches (total distance and time spent standing, walking, and at low- and high-intensity running speed). Training load, as quantified by heart rate and rating of perceived exertion, was recorded during all training sessions and was similar between groups. There were significant improvements in aerobic fitness and match performance in both groups of soccer players, especially in response to the first 4 weeks of pre-season training. However, no significant differences between specific and generic aerobic interval training were found in any of the measured variables including soccer specific tests. The results of this study showed that both small-sided games and running are equally effective modes of aerobic interval training in junior soccer players.     

Basic recruit training: health risks and opportunities

The present review examines the impact of basic recruit training on health and lifestyle. Many of those recruited begin training with a less than optimal lifestyle with respect to fitness, smoking habits, alcohol consumption, drug abuse, and exposure to sexually transmitted diseases. Thus, there is scope to enhance training programs that address fitness and lifestyle, minimizing potential losses in health and efficiency from upper respiratory infections, musculoskeletal injuries, cardiac catastrophes, mental disturbances, and adverse responses to extreme environments.     

Limitations to aerobic performance in mammals: interaction of structure and demand

In this paper we have explored the linked series of structures that collectively comprise the respiratory system. In examining each of these structural resistors, some seem to be primarily fixed, for example, the trachea, while others must be primarily variable or adaptable, for example, the cardiovascular system. Those structures that are truly variable will not be maintained with structural capacity in excess of their functional demand. As a consequence, these structures are the ones that may most often appear to be limiting O2 uptake. However, we question under which in vivo circumstances the most plastic steps in the cascade of resistances will impart the single-step limitation to O2 uptake. When reviewed in this context, available experimental evidence suggests that among the most athletic animals (those with the greatest weight-specific VO2), the respiratory resistors are likely tuned rather than dominated by a single-step limitation. Skeletal muscle must set the demand for O2 in exercising animals; hence, the relationship between total skeletal muscle mitochondria and maximum O2 consumption is quantitatively consistent, spanning broad differences in body size and aerobic capacity. Those respiratory structures that are primarily nonadaptable must be built with enough "excess structure" to accommodate potential adaptation in an animal's aerobic capacity during its lifetime. Consequently, the least aerobic animals will always appear to experience a limitation to VO2max in one of the most plastic or adaptable structures. We suggest that the adaptable structures upstream to the muscle mitochondria are built and maintained at a cost-benefit maximum ("structural efficiency") in all species. This differs from the concept of optimal structural design or symmorphosis.     

Physical and psychological stressors linked with stress fractures in recruit training

This study aimed to measure ambulation in infantry army basic training, and to evaluate if covering more distance can explain stress fractures in a stressor–stress model. Forty‐four male combat recruits (18.7 ± 0.7 years) participated in a 6‐month rigorous high intensity combat training program. Baseline data included anthropometric measurements, VO₂max, and psychological questionnaires. Actual distance covered was measured using a pedometer over an 11‐week training period. Psychological questionnaires were repeated after 2 months. Sixteen recruits were diagnosed with stress fractures by imaging (SFi = 36.4%). Statistical analysis included comparing measured variables between SFi and those without stress fractures (NSF). The recruits covered 796 ± 157 km, twofold the distance planned of 378 km (P < 0.001). The SFi group covered a distance 16.4% greater than that of the NSF group (866 ± 136 and 744 ± 161 km, respectively, P < 0.01), and also demonstrated greater psychological stress. These data reveal the importance of adherence to or enforcement of military training programs. In the light of these data, the Israeli Defense Forces program needs reappraisal. A stressor–stress response might explain the susceptibility of certain recruits for injury. Using advanced technology, monitoring ambulation may prevent stress fracture development by limiting subjects exceeding a certain level. Psychological profile may also play a role in predicting stress fracture development.