Incremental Treadmill Running Research Articles

High-Intensity Exercise Induced Oxidative Stress and Skeletal Muscle Damage in Postpubertal Boys and Girls: A Comparative Study

Pal, S, Chaki, B, Chattopadhyay, S, and Bandyopadhyay, A. High-intensity exercise induced oxidative stress and skeletal muscle damage in post-pubertal boys and girls: a comparative study. J Strength Cond Res 32(4): 1045-1052, 2018-The purpose of this study was to examine the sex variation in high-intensity exercise induced oxidative stress and muscle damage among 44 sedentary postpubertal boys and girls through estimation of postexercise release pattern of muscle damage markers like creatine kinase, lactate dehydrogenase (LDH), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and oxidative stress markers like extent of lipid peroxidation (thiobarbituric acid-reactive substances) and catalase activity. Muscle damage markers like creatine kinase, LDH, ALT, and AST were measured before, immediately after, and 24 and 48 hours after high-intensity incremental treadmill running. Oxidative stress markers like thiobarbituric acid-reactive substances and catalase activity were estimated before and immediately after the exercise. Lipid peroxidation and serum catalase activity increased significantly in both groups after exercise (p < 0.001) with postexercise values and percentage increase significantly higher in postpubertal boys as compared to girls (p < 0.001). Creatine kinase and LDH activity also increased significantly above pre-exercise level at 24 and 48 hours after exercise in both the sexes, (p < 0.001) with values significantly higher for boys than the girls (p < 0.001). Although ALT and AST increased significantly in both the groups after exercise, the pattern of postexercise release of these markers were found to be similar in both the groups. Accordingly, it has been concluded from the present investigation that high-intensity exercise induces significant oxidative stress and increases indices of skeletal muscle damage in both postpubertal girls and boys. However, postpubertal girls are relatively better protected from oxidative stress and muscle damage as compared to the boys of similar age and physical activity level. It is further evident that sex difference may not be apparent for all the biomarkers of muscle damage in this age group.

High-intensity intermittent \u201c5\u201310\u201315\u201d running reduces body fat, and increases lean body mass, bone mineral density, and performance in untrained subjects

The present study examined the effect of intense intermittent running with 5 s sprints on body composition, fitness level, and performance in untrained subjects aged 36–53 years. For 7 weeks, the subjects carried out 3 days a week 5–10–15 training consisting of 3–9 blocks of 4 repetitions of 15, 10, and 5 s low-, moderate-, and high-speed running, respectively. Body fat mass was 4.3% lower (P < 0.01), and lean body mass and bone mineral density was 1.1 and 0.9% higher (P < 0.01), respectively, after compared to before the intervention period (INT). The plasma bone turnover markers osteocalcin increased (P < 0.01) by 147%, and procollagen-type I N propeptide and carboxy-terminal collagen crosslinks increased (P < 0.05) by 84 and 76%, respectively. Furthermore, the training improved performance in 1500 m (P < 0.001), 3 km (P < 0.001), Yo–Yo intermittent endurance test (P < 0.01), and incremental treadmill running (P < 0.001) by 8.1, 9.9, 17.2, and 23.9%, respectively. Furthermore, blood lactate after running at 85% of maximal aerobic speed was lower (P < 0.01) after compared to before the INT. Thus, 7 weeks of 5–10–15 training resulted in significant health beneficial changes and better performance in untrained subject.

Reliable and sensitive physical testing of elite trapeze sailors.

It was investigated whether a newly developed discipline-specific test for elite-level trapeze sailors is reliable and sensitive. Furthermore, the physical demands of trapeze sailing were examined. In part 1, 9 national team athletes were accustomed to a simulated sailing test, which subsequently was completed on 4 occasions to determine test reliability and sensitivity to manipulations in body weight. Rope-pulling mean power output (MPO), oxygen consumption (VO2 ), heart rate (HR), and blood lactate values were acquired in all trials. In part 2, 6 sailors completed on-water racing with concurrent measurements of VO2 , HR, and blood lactate. VO2max was determined during an incremental treadmill running test. Typical error, minimal difference, and ICC for average MPO in the test were 1.3%, 1.7%, and 0.99%, respectively. Adding 4kg of external body weight caused a decrease in average MPO (270±45W vs 265±45W, P<.05) and an increase in VO2 (2.44±0.23L·min-1 vs 2.55±0.26L·min-1 , P<.01). VO2 , HR, and blood lactate during on-water sailing were 54.5%±7.2% VO2max , 75.1%±3.1% HRmax , and 5.8±2.7mmol·L-1 , respectively. However, VO2 and HR were substantially higher for periods of the race as peak values were 83.5%±11.4% and 89.9%±1.7% of max, respectively. In conclusion, the present test is reliable and sensitive, thus providing a sailing-specific alternative to traditional physical testing of elite trapeze sailors. Additionally, on-water racing requires moderate aerobic energy production, although oxygen consumption can approach maximal levels for short periods of time.

Moderate intensity, exercise-induced catecholamine release in the preoptic area and anterior hypothalamus in rats is enhanced in a warm environment

Thermoeffector responses and core body temperature (Tcore) homeostasis during exercise are affected by both ambient temperature and exercise intensity. We have previously reported that Tcore, heat loss responses, and catecholamine release in the preoptic area and anterior hypothalamus (PO/AH) increased during incremental treadmill running. However, no previous study has examined whether changes in the thermoregulatory responses at warm ambient temperature are related to catecholamine responses during moderate intensity exercise in rats. Therefore, the aim of the present study was to investigate the responsiveness of neurotransmission in the PO/AH to moderate intensity exercise at different ambient temperatures, and to relate this to changes in thermoregulation. We measured the monoamine levels in the PO/AH and the thermoregulatory responses in exercising rats simultaneously using a combination of methods, including in vivo microdialysis, biotelemetry, and animal O2/CO2 metabolism measuring system. On the day of experiments, rats ran for 60min at a speed of 18mmin−1 on a treadmill at a 5% gradient, in an ambient temperature of 23°C or 30°C. Tcore, tail skin temperature (Ttail; an index of heat loss), and oxygen consumption (V̇O2: an index of heat production) were monitored. Dopamine (DA), noradrenaline (NA), and serotonin (5-HT) levels were measured by high performance liquid chromatography (HPLC) with electrochemical detection. Exercise significantly increased the Tcore, Ttail, and V̇O2 values, as well as DA and NA release in the PO/AH at both temperatures, and the increases were more pronounced at the warm ambient temperature. The results suggest that the increase in the Tcore, heat production, and heat loss responses even during moderate intensity running in a warm environment are likely associated with an increase in DA and NA release in the PO/AH region.

Sex and maturity status affected the validity of a submaximal cycle test inadolescents.

This study assessed the validity and reliability of the Ekblom-Bak (EB) submaximal cycle test in adolescents and identified any sex- or maturity-related factors for prediction errors. We recruited 50 healthy subjects through a public announcement in Stockholm, Sweden, in 2016. The 27 boys and 23 girls were aged 10-15 years and in Tanner stages I-IV. They performed an EB test and incremental treadmill running test for direct measurement of maximal oxygen uptake (VO2 max). The estimation error of VO2 max was 0.09L/min. The correlation (r) was 0.86, and the standard error of the estimate (SEE) was 0.29L/min. The largest overestimation was seen in prepubertal boys (0.49L/min). The best precision of the EB test was achieved when boys in Tanner stages I and II were re-calculated using the prediction equationdeveloped for adult women. This yielded a mean difference of -0.05L/min, r=0.92 and SEE 0.23L/min, in the entire sample. The prediction error was lowered in boys, but not girls, with increasing pubertal maturity. The EB test was reasonably valid in adolescents, seemed to be related to sex and maturity status, and our findings support its use.

Gross efficiency predicts a 6-min double-poling ergometer performance in recreational cross-country skiers

The purpose of the study was to investigate which physiological parameters would most accurately predict a 6-min, all-out, double-poling (DP) performance in recreational cross-country skiers. Twelve male recreational cross-country skiers performed tests consisting of three series lasting 10 s, one lasting 60 s, plus a 6-min, all-out, DP performance test to estimate mean and peak power output. On a separate day, gross mechanical efficiency (GE) was estimated from a 10-min, submaximal, DP test and maximal oxygen consumption (VO2 max) was estimated from an incremental treadmill running test. Power was measured after each stroke from the acceleration and deceleration of the flywheel that induced the friction on the ergometer. The power was shown to the skier on a small computer placed on the ergometer. A multivariable correlation analysis showed that GE most strongly predicted 6-min DP performance (r = 0.79) and interestingly, neither DP VO2 max, nor treadmill-running VO2 max, correlated with 6-min DP performance. In conclusion, GE correlated most strongly with 6-min DP performance and GE at the ski ergometer was estimated to be 6.4 ± 1.1%. It is suggested that recreational cross-country skiers focus on skiing technique to improve gross mechanical efficiency during intense DP.

Application of the neuromuscular fatigue threshold treadmill test to muscles of the quadriceps and hamstrings

PurposeThe purposes of the present study were: (1) to determine whether the physical working capacity at the fatigue threshold (PWCFT) model that has been used for estimating the onset of neuromuscular fatigue in the vastus lateralis (VL) during incremental treadmill running could also be applied to the vastus medialis (VM), biceps femoris (BF), and semitendinosus (ST) muscles; and (2) if applicable, to compare the running velocities associated with the PWCFT among these muscles. MethodsEleven subjects (age 21.7 ± 1.8 years) performed an incremental treadmill test to exhaustion with electromyographic signals recorded from the VL, VM, BF, and ST. ResultsThe results indicated there were no significant (p > 0.05) mean differences in the running velocities associated with the PWCFT for the VL (14.4 ± 2.0 km/h), VM (14.3 ± 1.9 km/h), BF (13.8 ± 1.8 km/h), and ST (14.7 ± 2.3 km/h). In addition, there were significant inter-correlations (r = 0.68–0.88) among running velocities associated with the PWCFT of each muscle. Individual results also indicated that 9 of the 11 subjects exhibited identical PWCFT values for at least 3 of the 4 muscles, but there were no uniform patterns for any intra-individual differences. ConclusionThe findings of the present study suggested that the PWCFT test is a viable method to identify neuromuscular fatigue in the quadriceps and hamstrings during incremental treadmill exercise and results in consistent PWCFT values among these muscles.

Physiological Performance Measures in Female Collegiate Soccer Players

Although participation in women’s soccer has increased dramatically in the last two decades, the research into the physiological demands and physical characteristics of players is limited. PURPOSE: To compare anaerobic and aerobic power in female intercollegiate soccer players with a reference group of elite international players. METHODS: Subjects were 28 members of a division I university women’s soccer team. Maximal aerobic power (VO2 max) was determined during an incremental treadmill run using a MOXUS metabolic measurement system. The Margaria-Kalaman power test was timed using switch mats to determine anaerobic power. Bone mineral density and percent body fat were determined by dual-energy X-ray absorptiometry (DEXA). Anaerobic power comparisons were made by converting literature values for vertical jump heights to watts by the Lewis formula. RESULTS: VO2 max was similar between the collegiate players and the reference group of international players (52.7 ± 5.8 vs 51.5 ± 3.3 ml/kg/min for collegiate and reference players respectively). Similarly, anaerobic power was not different between the collegiate and the international players (841.2 ± 112.4 vs 808.8 ± 109.5 watts). Height (165 ± 6 vs 169 ± 2 cm) and mass (61 ± 7 vs 61 ± 2) were similar between the two groups; however the collegiate players had a higher percent body fat than the reference players (25.9 ± 5.2 vs 17.5 ± 2.6 %). CONCLUSION: These results suggest that the female collegiate players have aerobic and anaerobic power comparable to that reported for international (primarily European) elite female soccer players. Although the collegiate players were of similar height and body mass as the international players, the collegians had considerably higher percent body fat.

Running Technique is an Important Component of Running Economy and Performance.

ABSTRACTDespite an intuitive relationship between technique and both running economy (RE) and performance, and the diverse techniques used by runners to achieve forward locomotion, the objective importance of overall technique and the key components therein remain to be elucidated.PurposeThis study aimed to determine the relationship between individual and combined kinematic measures of technique with both RE and performance.MethodsNinety-seven endurance runners (47 females) of diverse competitive standards performed a discontinuous protocol of incremental treadmill running (4-min stages, 1-km·h−1 increments). Measurements included three-dimensional full-body kinematics, respiratory gases to determine energy cost, and velocity of lactate turn point. Five categories of kinematic measures (vertical oscillation, braking, posture, stride parameters, and lower limb angles) and locomotory energy cost (LEc) were averaged across 10–12 km·h−1 (the highest common velocity < velocity of lactate turn point). Performance was measured as season's best (SB) time converted to a sex-specific z-score.ResultsNumerous kinematic variables were correlated with RE and performance (LEc, 19 variables; SB time, 11 variables). Regression analysis found three variables (pelvis vertical oscillation during ground contact normalized to height, minimum knee joint angle during ground contact, and minimum horizontal pelvis velocity) explained 39% of LEc variability. In addition, four variables (minimum horizontal pelvis velocity, shank touchdown angle, duty factor, and trunk forward lean) combined to explain 31% of the variability in performance (SB time).ConclusionsThis study provides novel and robust evidence that technique explains a substantial proportion of the variance in RE and performance. We recommend that runners and coaches are attentive to specific aspects of stride parameters and lower limb angles in part to optimize pelvis movement, and ultimately enhance performance.

Allometric scaling of body mass in running economy data: An important consideration in modeling marathon performance

The purpose of this study was to compare metabolic variables during submaximal running as predictors of marathon performance. Running economy (RE) and respiratory exchange ratio (RER) data were gathered during a 30 min incremental treadmill run completed within 2 weeks prior to running a 42.2-km marathon. Paces during the treadmill run progressed every 5 min from 75-100% of 10-km race velocity. Variables at each stage were analyzed as predictors of relative marathon performance (RMP) in competitive (COMP) and recreational (REC) runners. Twenty-nine runners were classified as COMP (n = 12; age 30 ± 8 years) or REC (n =17; age 20 ± 1 year) based on performance in shorter races. RMP was calculated as percent difference from predicted marathon finish time. Two methods of calculating RE were used: unscaled (ml . kg -1. km -1 ) and with allometric scaling of body mass (ml . kg -0.75. km -1 ). The COMP runners were significantly more economical than REC ( p =0.005; p =0.015 with scaling). For the whole population, RE with and without scaling was significantly correlated with RMP. Within groups, RMP was not significantly correlated with RE unless scaling was used: COMP runners at 75% ( p =0.044), 80% ( p =0.040), and REC runners at 85% ( p =0.038). Runners classified as COMP were more economical than REC, but RER was not different. The use of allometric scaling is important when assessing homogeneous groups. In this study, allometrically-scaled RE at 80-85% of 10-km velocity was the best predictor of RMP within groups.

Testing Game-Based Performance in Team-Handball.

Wagner, H, Orwat, M, Hinz, M, Pfusterschmied, J, Bacharach, DW, von Duvillard, SP, and Müller, E. Testing game-based performance in team-handball. J Strength Cond Res 30(10): 2794-2801, 2016-Team-handball is a fast paced game of defensive and offensive action that includes specific movements of jumping, passing, throwing, checking, and screening. To date and to the best of our knowledge, a game-based performance test (GBPT) for team-handball does not exist. Therefore, the aim of this study was to develop and validate such a test. Seventeen experienced team-handball players performed 2 GBPTs separated by 7 days between each test, an incremental treadmill running test, and a team-handball test game (TG) (2 × 20 minutes). Peak oxygen uptake (V[Combining Dot Above]O2peak), blood lactate concentration (BLC), heart rate (HR), sprinting time, time of offensive and defensive actions as well as running intensities, ball velocity, and jump height were measured in the game-based test. Reliability of the tests was calculated using an intraclass correlation coefficient (ICC). Additionally, we measured V[Combining Dot Above]O2peak in the incremental treadmill running test and BLC, HR, and running intensities in the team-handball TG to determine the validity of the GBPT. For the test-retest reliability, we found an ICC >0.70 for the peak BLC and HR, mean offense and defense time, as well as ball velocity that yielded an ICC >0.90 for the V[Combining Dot Above]O2peak in the GBPT. Percent walking and standing constituted 73% of total time. Moderate (18%) and high (9%) intensity running in the GBPT was similar to the team-handball TG. Our results indicated that the GBPT is a valid and reliable test to analyze team-handball performance (physiological and biomechanical variables) under conditions similar to competition.

Formula omitted] assessment in athletes: A thorough method comparison study between Yo-Yo test and direct measurement

IntroductionAlthough different studies have reported limits of agreement in assessing V˙O2max between the Yo-Yo test and the direct measurement, the precision of these limits in general has not been considered. The aim of this study was to examine the extent of agreement in the assessment of V˙O2max in athletes between the Yo-Yo endurance test (YET) and the direct measurement (DM), and to quantify the precision of the estimated limits of agreement. Material and methodsData were obtained from a group of 11 male field hockey players (Age=22.2±3.6 yrs, BMI=22.1±2.4kgm−2). DM was performed using an incremental treadmill running test. YET level 1 was used for indirect estimation of V˙O2max. Bland–Altman analysis was employed for assessing agreement between the two methods. The acceptable 95% limits of agreement were set a priori at ±5mlkg−1min−1. ResultsA non-statistically significant bias was observed between YET and DM (50.78 vs. 51.09mlkg−1min−1, P>.05). The estimates of the 95% limits of agreement were −4.34 and 3.72mlkg−1min−1. And the 95% confidence intervals for these limits were from −6.78 to −1.90mlkg−1min−1, and from 1.29 to 6.16mlkg−1min−1, respectively. The difference between methods did not appear to be correlated to the magnitude of measurement. ConclusionsA reasonably good agreement was found between YET and DM. However, the large variance of the limits of agreement due to the small sample size means these results should be treated with caution.

Recovery levels after eccentric and concentric loading in maximal force.

[Purpose] The aim of this study was to compare the differences in recovery periods after maximal concentric and eccentric exercises. [Subjects and Methods] Twenty-two participants voluntarily participated and were divided into two groups: the athlete and sedentary groups. An incremental treadmill running test was performed until exhaustion. During the subsequent passive recovery session, heart rate and venous blood lactate level were determined every 3 minutes until the venous blood lactate level reached 2 mmol/l. The same test protocol was implemented 15 days later. [Results] Both groups showed significantly shorter running durations in concentric exercise, while significant differences were found between the athlete and sedentary groups in terms of venous blood lactate level responses. In addition, there were significant differences between the athlete and sedentary groups in terms of running duration and heart rate in concentric and eccentric exercises. [Conclusion] The present study revealed no difference between the athlete and sedentary groups in terms of recovery durations after eccentric and concentric loadings, although the athletes demonstrated faster recovery in terms of HR compared with the sedentary group. It was thought that concentric exercises cause greater physiological responses.

Mucosal immunity and upper respiratory tract symptoms in recreational endurance runners.

The present study investigated the effects of a 12-week endurance-training intervention on salivary proteins and upper respiratory tract symptoms (URS) in 25 young men. Saliva samples of 25 recreational male endurance runners (age 34.6 years, body mass index = 23.8 kg·m(-2), peak aerobic capacity = 47.2 mL·kg(-1)·min(-1)) were collected before (PRE) and after (POST) the training intervention, in a fasting state, as well as both before and after a maximal incremental treadmill run. The training consisted of both continuous and interval training sessions, 4-6 times per week based on the polarized training approach. Participants filled in Wisconsin Upper Respiratory Symptom Survey-21 and were retrospectively divided into 2 groups according to whether they reported URS (URS group, n = 13) or not (HEALTHY group, n = 12). Basal salivary immunoglobulin A (sa-sIgA) levels were significantly higher (+70%, p < 0.05) in the HEALTHY group both at PRE and POST whereas no significant differences were observed in salivary immunoglobulin M, salivary immunoglobulin G, lysozyme, or salivary α-amylase activity (sAA). Sa-sIgA concentration at PRE significantly correlated with the number of sick-days (R = -0.755, p < 0.001) in all subjects. The incremental treadmill run acutely increased sAA significantly (p < 0.05) at PRE (200%) and POST (166%) in the HEALTHY group but not in the URS group. This study demonstrated that subjects, who experienced URS during the 12 weeks of progressive endurance training intervention, had significantly lower basal sa-sIgA levels both before and after the experimental endurance training period. In addition to sa-sIgA, acute sAA response to exercise might be a possible determinant of susceptibility to URS in endurance runners.

Influência do modelo alométrico na relação entre consumo máximo de oxigênio e desempenho de corredores fundistas

The aim was investigated the effect of allometric model in relationship between maximal Oxygen uptake (VO2max) and long‐distance running performance. Twelve runners (age: 28.6±7.4 years, body mass: 67.9±9.4kg, height: 1.71±0.7m) were submitted to an incremental treadmill running protocol for determination of VO2max and participated in a trail of 10.000m. despite the significant differences found between the forms of relativization of VO2max (by total body mass, allometric exponent for sampling and lean body mass), the strong correlations verified between VO2max and performance show that this prediction is independent of how the VO2max is relativized.

Utility of electromyographic fatigue threshold during treadmill running.

We investigated 2 different methods for determining muscle fatigue threshold by electromyography (EMG). Thirteen subjects completed an incremental treadmill running protocol for EMG fatigue threshold (EMGFT ) determination based on the critical power concept (EMGFT 1) and the breakpoint in the linear relationship between EMG amplitude and exercise intensity (EMGFT 2). Then, both the EMGFT 1 and EMGFT 2 were tested in a continuous treadmill running protocol. EMG was recorded from the rectus femoris (RF), vastus lateralis (VL), biceps femoris (BF), and lateral gastrocnemius (LG) muscles. For BF, EMGFT 2 was higher than EMGFT 1, and EMGFT 1 for BF was lower than EMGFT 1 for LG. EMG of RF was higher at EMGFT 2 than at EMGFT 1, and LG EMG was lower at EMGFT 2. EMGFT can be determined during a single treadmill running test, and EMGFT 1 may be the most appropriate method to estimate the muscle fatigue threshold during running.

Neuromuscular Responses Of The Quadriceps Femoris And Hamstring Muscles During Incremental Treadmill Running

PURPOSE: The purpose of the present study was to examine the patterns of responses for the electromyographic (EMG) amplitude versus oxygen uptake (VO2) relationships from muscles of the quadriceps femoris and hamstrings during incremental treadmill running. METHODS: Thirteen aerobically-trained males (mean age ± SD = 21.4 ± 1.4 yrs, body mass = 73.8 ± 7.0 kg, 6.8 ± 2.5 aerobic training hr·wk-1, 58.4 ± 49.6 running km·wk-1) volunteered to perform an incremental treadmill test to exhaustion that began at 9.7 km·h-1 and increased 1.6 km·h-1 every two minutes. Following the 14.5 km·h-1 stage, the grade was increased 2.5% every two minutes until volitional fatigue. Expired gas samples were collected and analyzed using a calibrated metabolic cart with VO2 values expressed as 30-second averages and normalized to peak oxygen uptake (VO2peak). Electromyographic samples were recorded using bipolar wireless electrode sensors that were placed on the right thigh over the vastus lateralis, rectus femoris, vastus medialis, biceps femoris, and semitendinosus muscles. Electromyographic amplitude (μVrms) values were calculated for 30-second epochs, normalized, and separately plotted across VO2 for each muscle and subject. Polynomial regression analyses were used to determine the best model fit (i.e. linear, quadratic, or cubic) for the EMG amplitude versus VO2 relationships for the composite data. RESULTS: The results of the polynomial regression analyses indicated there were significant (P < 0.05) increases in EMG amplitude across VO2 for the vastus lateralis (linear, r = 0.970), rectus femoris (cubic, r = 0.976), vastus medialis (quadratic, r = 0.997), biceps femoris (cubic, r = 0.999), and semitendinosus muscles (linear, r = 0.992). CONCLUSIONS: The findings of the present study indicated that the patterns of responses (i.e. linear, quadratic, cubic) for muscle activation (EMG amplitude) versus exercise intensity (VO2) appear to be unique among muscles of the thigh and may be due to variations in muscle architecture, fiber type, or biomechanical differences. In addition, these patterns of responses for muscle activation relative to exercise intensity may provide foundational data related to the assessment of neuromuscular fatigue in the quadriceps femoris and hamstring muscles during incremental treadmill running.

The correlation between running economy and maximal oxygen uptake: cross-sectional and longitudinal relationships in highly trained distance runners.

A positive relationship between running economy and maximal oxygen uptake (V̇O2max) has been postulated in trained athletes, but previous evidence is equivocal and could have been confounded by statistical artefacts. Whether this relationship is preserved in response to running training (changes in running economy and V̇O2max) has yet to be explored. This study examined the relationships of (i) running economy and V̇O2max between runners, and (ii) the changes in running economy and V̇O2max that occur within runners in response to habitual training. 168 trained distance runners (males, n = 98, V̇O2max 73.0 ± 6.3 mL∙kg-1∙min-1; females, n = 70, V̇O2max 65.2 ± 5.9 mL kg-1∙min-1) performed a discontinuous submaximal running test to determine running economy (kcal∙km-1). A continuous incremental treadmill running test to volitional exhaustion was used to determine V̇O2max 54 participants (males, n = 27; females, n = 27) also completed at least one follow up assessment. Partial correlation analysis revealed small positive relationships between running economy and V̇O2max (males r = 0.26, females r = 0.25; P<0.006), in addition to moderate positive relationships between the changes in running economy and V̇O2max in response to habitual training (r = 0.35; P<0.001). In conclusion, the current investigation demonstrates that only a small to moderate relationship exists between running economy and V̇O2max in highly trained distance runners. With >85% of the variance in these parameters unexplained by this relationship, these findings reaffirm that running economy and V̇O2max are primarily determined independently.

Relationship between perceived exertion and blood lactate concentrations during incremental running test in young females.

BackgroundTo investigate more practical handling of Borg’s ratings of perceived exertion (RPE) and category-ratio scale of RPE (CR-10), we evaluated interrelationships between RPE, CR-10, and blood lactate concentrations (bLa) during incremental treadmill running tests for young females with different aerobic fitness levels.MethodsOxygen consumption, heart rate, bLa, RPE, and CR-10 were measured from distance runners (DR; n = 15), race walkers (RW; n = 6), and untrained females (UT; n = 11). These variables corresponding to the lactate threshold (LT) and onset of blood lactate accumulation (OBLA) were compared among these groups.ResultsThe UT had significantly lower RPE at LT than DR and RW, although the CR-10 at LT was not significantly different among these groups. The CR-10 at OBLA was significantly lower for the UT than DR. The relationship between bLa and CR-10 was approximated well by two linear regression lines in all groups. The bLa at the intersection only for the RW was significantly lower than that at LT, however, such intersections were observed at CR-10 = 3.1 to 3.2 without significant group differences. The CR-10 scores at LT and intersections were not significantly different in each group.ConclusionThese results suggested that an intersection between CR-10 and bLa was observed at the CR-10 score around three points of first half regardless of the aerobic fitness levels in young females, and such CR-10 scores would be associated with LT.

Effect of Rest Method on Fatigue Related Factors and Performance after Submaximal Exercise

The purpose of this study was to investigate the effects of rest method on fatigue related factors and performance after submaximal exercise. Twenty seven collegians participated in this study. All subjects performed an incremental treadmill running exercise, not to be able to perform exercise more on a treadmill. Each subject was relaxed for 10 minutes in the way of rest one of the relaxing 3 ways (sitting, lying, and jogging) after submaximal exercise, and it was made to the cycling movement again. The present study shows that fatigue related factors such as lactate, ammonia, glucose, and free radical were significantly decreased after active rest (jogging). On the other hand, the antioxidant capacity shows high level. There was no change of heart rate according to the rest type during the recovery period, 10 minutes. The heart rate, lactate, ammonia, and free radical show low level in the next exercise performance after the rest of activity. On the contrary to this the antioxidant and VO2 max show high level. Also, motor performances such as VO2 max and antioxidant capacity were significantly higher at active rest than passive rest. In conclusion, active rest is to show the fatigue substance lower than that of passive rest method, it was found that the performance capabilities of the next can be improved.Keywords: Antioxidant, Active Rest, Free Radical, Lactate, Passive Rest