Fit women are not able to use the whole aerobic capacity during aerobic dance

Edvardsen, E, Ingjer, F, and B?, K. Fit women are not able to use the whole aerobic capacity during aerobic dance. J Strength Cond Res 25(12): 3479-3485, 2011-This study compared the aerobic capacity during maximal aerobic dance and treadmill running in fit women. Thirteen well-trained female aerobic dance instructors aged 30 ± 8.17 years (mean ± SD) exercised to exhaustion by running on a treadmill for measurement of maximal oxygen uptake (VO(2)max) and peak heart rate (HRpeak). Additionally, all subjects performed aerobic dancing until exhaustion after a choreographed videotaped routine trying to reach the same HRpeak as during maximal running. The p value for statistical significance between running and aerobic dance was set to ≤0.05. The results (mean ± SD) showed a lower VO(2)max in aerobic dance (52.2 ± 4.02 ml·kg·min) compared with treadmill running (55.9 ± 5.03 ml·kg·min) (p = 0.0003). Further, the mean ± SD HRpeak was 182 ± 9.15 b·min in aerobic dance and 192 ± 9.62 b·min in treadmill running, giving no difference in oxygen pulse between the 2 exercise forms (p = 0.32). There was no difference in peak ventilation (aerobic dance: 108 ± 10.81 L·min vs. running: 113 ± 11.49 L·min). In conclusion, aerobic dance does not seem to be able to use the whole aerobic capacity as in running. For well endurance-trained women, this may result in a lower total workload at maximal intensities. Aerobic dance may therefore not be as suitable as running during maximal intensities in well-trained females.     

Specific alterations of physiological parameters in competitive race walkers

Race walking is the technical and athletic expression of fast walking and it can be considered as a type of endurance performance. The purpose of this study was to examine whether 12 weeks of a specially designed training program results in the further training enhancement of endurance performance and the related physiological parameters in already well-trained race walkers competing at the national and international level. The investigation protocol consisted of determining the maximal oxygen uptake (VO2peak) and related gas exchange values using an automated cardiopulmonary exercise system and of determining blood lactate variables (aerobic threshold - LTAer and the maximal lactate steady state - MLSS) during walking with proper technique at 8, 10, 12 and 14 km·h-1 for 4 minutes without rest in between. Thereafter, the speed on the treadmill was increased by 0.5 km·h-1 every two minutes until exhaustion to determine VO2peak. After 12 weeks of a specially designed endurance training, statistically significant increases in VO2peak (61.8±8.5 mL·kg-1·min-1 pre vs. 66.9±9.5 mL·kg-1·min-1 post training; p<0.05) and blood lactate variables (VO2-LTAer and VO2-MLSS; p<0.05) were noted. The obtained results suggest that the applied training program can improve endurance and race performance in previously well trained race walkers.     

Prior eccentric exercise reduces v[combining dot above]o2peak and ventilatory threshold but does not alter movement economy during cycling exercise

Exercise-induced muscle damage (EIMD) has been shown to reduce force production and result in delayed-onset soreness and pain in the damaged muscle(s). Cycling in the presence of EIMD reduces peak power output and time-trial performance. However, its effect on peak aerobic capacity has not been widely studied. The purpose of this study was to examine the impact of EIMD targeted specifically to the quadriceps muscle group on peak oxygen consumption (V[Combining Dot Above]O2peak) during cycling. Ten participants (4 men, 6 women) completed a V[Combining Dot Above]O2peak test on a cycle ergometer before and 48 hours after performing 24 eccentric contractions with their right and left quadriceps with a weight equal to 120% of 1-repetition maximal concentric strength (1RM). The EIMD was assessed using 1RM, and muscle soreness was assessed using a 100-mm visual analog scale. The presence of EIMD was confirmed by a 9% reduction in 1RM (p = 0.0001) and increased ratings of soreness from 2.4 ± 2.1 to 24.6 ± 10.8 mm (p = 0.001). The V[Combining Dot Above]O2peak was reduced from 46.2 ± 9.7 to 41.8 ± 10.7 ml·kg·min (10%; p = 0.01) with participants terminating exercise at lower heart rates 191 ± 9 vs. 186 ± 10 b·min (p = 0.02) and power output 248 ± 79 vs. 238 ± 81 W (p = 0.02) after EIMD. Additionally, ventilatory threshold decreased from 34.2 ± 7.8 to 30.5 ± 8.5 ml·kg·min (11%; p = 0.031). Despite the reduction in V[Combining Dot Above]O2peak, cycling economy (p = 0.17) did not differ pre-EIMD and post-EIMD. These findings indicate that EIMD reduced peak aerobic exercise capacity to an extent that could result in meaningful reductions in exercise performance. The reduction is likely attributable to a combination of reduced strength, earlier accumulation of lactic acid, and heightened muscle pain during exercise.     

Effects of a concurrent strength and endurance training on running performance and running economy in recreational marathon runners

The purpose of this study was to investigate the effects of a concurrent strength and endurance training program on running performance and running economy of middle-aged runners during their marathon preparation. Twenty-two (8 women and 14 men) recreational runners (mean ± SD: age 40.0 ± 11.7 years; body mass index 22.6 ± 2.1 kg·m?2) were separated into 2 groups (n = 11; combined endurance running and strength training program [ES]: 9 men, 2 women and endurance running [E]: 7 men, and 4 women). Both completed an 8-week intervention period that consisted of either endurance training (E: 276 ± 108 minute running per week) or a combined endurance and strength training program (ES: 240 ± 121-minute running plus 2 strength training sessions per week [120 minutes]). Strength training was focused on trunk (strength endurance program) and leg muscles (high-intensity program). Before and after the intervention, subjects completed an incremental treadmill run and maximal isometric strength tests. The initial values for VO2peak (ES: 52.0 ± 6.1 vs. E: 51.1 ± 7.5 ml·kg?1·min?1) and anaerobic threshold (ES: 3.5 ± 0.4 vs. E: 3.4 ± 0.5 m·s?1) were identical in both groups. A significant time × intervention effect was found for maximal isometric force of knee extension (ES: from 4.6 ± 1.4 to 6.2 ± 1.0 N·kg?1, p < 0.01), whereas no changes in body mass occurred. No significant differences between the groups and no significant interaction (time × intervention) were found for VO2 (absolute and relative to VO2peak) at defined marathon running velocities (2.4 and 2.8 m·s?1) and submaximal blood lactate thresholds (2.0, 3.0, and 4.0 mmol·L?1). Stride length and stride frequency also remained unchanged. The results suggest no benefits of an 8-week concurrent strength training for running economy and coordination of recreational marathon runners despite a clear improvement in leg strength, maybe because of an insufficient sample size or a short intervention period.     

VO₂ requirements of boxing exercises

The purpose of this study was to quantify the physiological requirements of various boxing exercises such as sparring, pad work, and punching bag. Because it was not possible to measure the oxygen uptake (VO?) of "true" sparring with a collecting gas valve in the face, we developed and validated a method to measure VO? of "true" sparring based on "postexercise" measurements. Nine experienced male amateur boxers (Mean ± SD: age = 22.0 ± 3.5 years, height = 176.0 ± 8.0 cm, weight = 71.4 ± 10.9 kg, number of fights = 13.0 ± 9.5) of regional and provincial level volunteered to participate in 3 testing sessions: (a) maximal treadmill test in the LAB, (b) standardized boxing training in the GYM, and (c) standardized boxing exercises in the LAB. Measures of VO?, heart rate (HR), blood lactate concentration [LA], rated perceived exertion level, and punching frequencies were collected. VO? values of 43.4 ± 5.9, 41.1 ± 5.1, 24.7 ± 6.1, 30.4 ± 5.8, and 38.3 ± 6.5 ml·kg?1·min?1 were obtained, which represent 69.7 ± 8.0, 66.1 ± 8.0, 39.8 ± 10.4, 48.8 ± 8.5, and 61.7 ± 10.3%VO?peak for sparring, pad work, and punching bag at 60, 120, and 180 b·min?1, respectively. Except for lower VO? values for punching the bag at 60 and 120 b·min?1 (p < 0.05), there was no VO? difference between exercises. Similar pattern was obtained for %HRmax with respective values of 85.5 ± 5.9, 83.6 ± 6.3, 67.5 ± 3.5, 74.8 ± 5.9, and 83.0 ± 6.0. Finally, sparring %HRmax and [LA] were slightly higher in the GYM (91.7 ± 4.3 and 9.4 ± 2.2 mmol·L?1) vs. LAB (85.5 ± 5.9 and 6.1 ± 2.3 mmol·L?1). Thus, in this study simulated LAB sparring and pad work required similar VO? (43-41 ml·kg?1·min?1, respectively), which corresponds to ~70%VO?peak. These results underline the importance of a minimum of aerobic fitness for boxers and draw some guidelines for the intensity of training.     

Effect of helium breathing on intercostal and quadriceps muscle blood flow during exercise in COPD patients

Emerging evidence indicates that, besides dyspnea relief, an improvement in locomotor muscle oxygen delivery may also contribute to enhanced exercise tolerance following normoxic heliox (replacement of inspired nitrogen by helium) administration in patients with chronic obstructive pulmonary disease (COPD). Whether blood flow redistribution from intercostal to locomotor muscles contributes to this improvement currently remains unknown. Accordingly, the objective of this study was to investigate whether such redistribution plays a role in improving locomotor muscle oxygen delivery while breathing heliox at near-maximal [75% peak work rate (WR(peak))], maximal (100%WR(peak)), and supramaximal (115%WR(peak)) exercise in COPD. Intercostal and vastus lateralis muscle perfusion was measured in 10 COPD patients (FEV(1) = 50.5 ± 5.5% predicted) by near-infrared spectroscopy using indocyanine green dye. Patients undertook exercise tests at 75 and 100%WR(peak) breathing either air or heliox and at 115%WR(peak) breathing heliox only. Patients did not exhibit exercise-induced hyperinflation. Normoxic heliox reduced respiratory muscle work and relieved dyspnea across all exercise intensities. During near-maximal exercise, quadriceps and intercostal muscle blood flows were greater, while breathing normoxic heliox compared with air (35.8 ± 7.0 vs. 29.0 ± 6.5 and 6.0 ± 1.3 vs. 4.9 ± 1.2 ml·min(-1)·100 g(-1), respectively; P < 0.05; mean ± SE). In addition, compared with air, normoxic heliox administration increased arterial oxygen content, as well as oxygen delivery to quadriceps and intercostal muscles (from 47 ± 9 to 60 ± 12, and from 8 ± 1 to 13 ± 3 mlO(2)·min(-1)·100 g(-1), respectively; P < 0.05). In contrast, normoxic heliox had neither an effect on systemic nor an effect on quadriceps or intercostal muscle blood flow and oxygen delivery during maximal or supramaximal exercise. Since intercostal muscle blood flow did not decrease by normoxic heliox administration, blood flow redistribution from intercostal to locomotor muscles does not represent a likely mechanism of improvement in locomotor muscle oxygen delivery. Our findings might not be applicable to patients who hyperinflate during exercise.     

The effects of static stretching on running economy and endurance performance in female distance runners during treadmill running

Stretching can lead to decreased muscle stiffness and has been associated with decreased force and power production. The purpose of this study was to investigate the acute effects of static stretching (SS) on running economy and endurance performance in trained female distance runners. Twelve long distance female (30 ± 9 years) runners were assessed for height (159.4 ± 7.4 cm), weight (54.8 ± 7.2 kg), % body fat (19.7 ± 2.8%), and maximal oxygen consumption (VO2max: 48.4 ± 5.1 ml·kg(-1)·min(-1)). Participants performed 2 sessions of 60-minute treadmill runs following a randomly assigned SS protocol or quiet sitting (QS). During the first 30 minutes (running economy), expired gases, heart rate (HR), and rating of perceived exertion (RPE) were recorded while the participant ran at 65% VO2max. During the final 30 minutes (endurance performance), distance covered, speed, HR, and RPE were recorded while the participant attempted to cover as much distance as possible. Repeated measures analyses of variance were performed on the data. Significance was accepted at p < 0.05. The SS measured by sit-and-reach increased flexibility (SS: 29.8 ± 8.3 vs. QS: 33.1 ± 8.1 cm) but had no effect on running economy (VO2: 33.7 ± 3.2 vs. 33.8 ± 2.3 ml·kg(-1)·min(-1)), calorie expenditure (270 ± 41 vs. 270 ± 41 kcal), HR (157 ± 10 vs. 160 ± 12 b·min(-1)), or endurance performance (5.5 ± 0.6 vs. 5.5 ± 0.7 km). These findings indicated that stretching did not have an adverse effect on endurance performance in trained women. This suggests that the performance decrements previously associated with stretching may not occur in trained women.     

Aging and factors related to running economy

The purpose of this study was to investigate the relationship that age has on factors affecting running economy (RE) in competitive distance runners. Fifty-one male and female subelite distance runners (Young [Y]: 18-39 years [n = 18]; Master [M]: 40-59 years [n = 22]; and Older [O]: 60-older [n = 11]) were measured for RE, step rate, lactate threshold (LT), VO2max, muscle strength and endurance, flexibility, power, and body composition. An RE test was conducted at 4 different velocities (161, 188, 215, and 241 m·min(-1)), with subjects running for 5 minutes at each velocity. The steady-state VO2max during the last minute of each stage was recorded and plotted vs. speed, and a regression equation was formulated. A 1 × 3 analysis of variance revealed no differences in the slopes of the RE regression lines among age groups (y = 0.1827x - 0.2974; R2 = 0.9511 [Y]; y = 0.1988x - 1.0416; R2 = 0.9697 [M]; y = 0.1727x + 3.0252; R2 = 0.9618 [O]). The VO2max was significantly lower in the O group compared to in the Y and M groups (Y = 64.1 ± 3.2; M = 56.8 ± 2.7; O = 44.4 ± 1.7 mlO2·kg(-1)·min(-1)). The maximal heart rate and velocity @ LT were significantly different among all age groups (Y = 197 ± 4; M = 183 ± 2; O = 170 ± 6 b·min(-1) and Y = 289.7 ± 27.0; M = 251.5 ± 32.9; O = 212.3 ± 24.6 m·min(-1), respectively). The VO2max @ LT was significantly lower in the O group compared to in the Y and M groups (Y = 50.3 ± 2.0; M = 48.8 ± 2.9; O = 34.9 ± 3.2 mlO2·kg(-1)·min(-1)). The O group was significantly lower than in the Y and M groups in flexibility, power, and upper body strength. Multiple regression analyses showed that strength and power were significantly related to running velocity. The results from this cross-sectional analysis suggest that age-related declines in running performance are associated with declines in maximal and submaximal cardiorespiratory variables and declines in strength and power, not because of declines in running economy.     

Physiological correlates of skating performance in women's and men's ice hockey

The purpose of the current investigation was to identify relationships between physiological off-ice tests and on-ice performance in female and male ice hockey players on a comparable competitive level. Eleven women, 24 ± 3.0 years, and 10 male ice hockey players, 23 ± 2.4 years, were tested for background variables: height, body weight (BW), ice hockey history, and lean body mass (LBM) and peak torque (PT) of the thigh muscles, VO2peak and aerobic performance (Onset of Blood Lactate Accumulation [OBLA], respiratory exchange ratio [RER1]) during an incremental bicycle ergometer test. Four different on-ice tests were used to measure ice skating performance. For women, skating time was positively correlated (p < 0.05) to BW and negatively correlated to LBM%, PT/BW, OBLA, RER 1, and VO2peak (ml O2·kg(-1) BW(-1)·min(-1)) in the Speed test. Acceleration test was positively correlated to BW and negatively correlated to OBLA and RER 1. For men, correlation analysis revealed only 1 significant correlation where skating time was positively correlated to VO2peak (L O2·min(-1)) in the Acceleration test. The male group had significantly higher physiological test values in all variables (absolute and relative to BW) but not in relation to LBM. Selected off-ice tests predict skating performance for women but not for men. The group of women was significantly smaller and had a lower physiological performance than the group of men and were slower in the on-ice performance tests. However, gender differences in off-ice variables were reduced or disappeared when values were related to LBM, indicating a similar capacity of producing strength and aerobic power in female and male hockey players. Skating performance in female hockey players may be improved by increasing thigh muscle strength, oxygen uptake, and relative muscle mass.     

Time to exhaustion and time spent at a high percentage of VO2max in severe intensity domain in children and adults

The aim of the study was to compare time spent at a high percentage of VO2max (>90% of VO2max) (ts90%), time to achieve 90% of VO2max (ta90%), and time to exhaustion (TTE) for exercise in the severe intensity domain in children and adults. Fifteen prepubertal boys (10.3 ± 0.9 years) and 15 men (23.5 ± 3.6 years) performed a maximal graded exercise to determine VO2max, maximal aerobic power (MAP) and power at ventilatory threshold (PVTh). Then, they performed 4 constant load exercises in a random order at PVTh plus 50 and 75% of the difference between MAP and PVTh (PΔ50 and PΔ75) and 100 and 110% of MAP (P100 and P110). VO2max was continuously monitored. The P110 test was used to determine maximal accumulated oxygen deficit (MAOD). No significant difference was found in ta90% between children and adults. ts90% and TTE were not significantly different between children and adults for the exercises at PΔ50 and PΔ75. However, ts90% and TTE during P100 (p < 0.05 and p < 0.01, respectively) and P110 (p < 0.001) exercises were significantly shorter in children. Children had a significantly lower MAOD than adults (34.3 ± 9.4 ml · kg vs. 53.6 ± 11.1 ml · kg). A positive relationship (p < 0.05) was obtained between MAOD and TTE values during the P100 test in children. This study showed that only for intensities at, or higher than MAP, lower ts90% in children was linked to a reduced TTE, compared to adults. Shorter TTE in children can partly be explained by a lower anaerobic capacity (MAOD). These results give precious information about exercise intensity ranges that could be used in children's training sessions. Moreover, they highlight the implication of both aerobic and anaerobic processes in endurance performances in both populations.     

Effects of strength, endurance, and concurrent training on aerobic power and dynamic neuromuscular economy in elderly men

The aim of this study was to investigate the effects of concurrent training on endurance capacity and dynamic neuromuscular economy in elderly men. Twenty-three healthy men (65 ± 4 years) were divided into 3 groups: concurrent (CG, n = 8), strength (SG, n = 8), and aerobic training group (EG, n = 7). Each group trained 3 times a week for 12 weeks, strength training, aerobic training, or both types of training in the same session. The maximum aerobic workload (Wmax) and peak oxygen uptake (VO2peak) of the subjects were evaluated on a cycle ergometer before and after the training period. Moreover, during the maximal test, muscle activation was measured at each intensity by means of electromyographic signals from the vastus lateralis (VL), rectus femoris (RF), biceps femoris long head, and gastrocnemius lateralis to determine the dynamic neuromuscular economy. After training, significant increases in VO2peak and Wmax were only found in the CG and EG (p < 0.05), with no difference between groups. Moreover, there was a significant decrease in myoelectric activity of the RF muscle at 50 (EG), 75 and 100 W (EG and CG) and in the VL for the 3 groups at 100 W (p < 0.05). No change was seen in the electrical signal from the lateral gastrocnemius muscle and biceps femoris. The results suggest specificity in adaptations investigated in elderly subjects, because the most marked changes in the neuromuscular economy occurred in the aerobically trained groups.     

Time course for recovery of peak aerobic power after blood donation

Peak aerobic power (VO2peak) is decreased after blood donation, but the time course for full recovery is unknown. We measured VO2peak and exercise time to fatigue before and weekly for 4 weeks after 450-ml blood donation at a blood donor clinic, to determine the time course of recovery. Twelve moderately active individuals (2 women, 10 men; 24.3 ± 5.2 years) of average aerobic fitness (based on their VO2peak relative to normative values) completed VO2peak exercise tests before donation, the day after donation, and at weekly intervals for 4 weeks after donation. VO2peak was determined by an incremental exercise test on a cycle ergometer. At baseline, mean absolute and relative VO2peak values were 4.06 ± 0.92 L·min(-1) and 46.6 ± 7.0 ml·kg(-1)·min(-1), respectively. VO2peak was significantly decreased on day 1 (3.85 ± 0.89 L·min(-1); 44.0 ± 6.5 ml·kg(-1)·min(-1)) and during week 2 (3.91 ± 0.97 L·min(-1); 44.5 ± 7.2 ml·kg(-1)·min(-1)) after blood donation (p < 0.05), and recovered at week 3 after donation. Time to fatigue and peak heart rate were not significantly affected by blood donation. We conclude that blood donation causes a significant decrease in VO2peak for between 2 and 3 weeks. The practical application of this study is that aerobic power in people of average fitness will be decreased, up to 3 weeks after donating blood. Despite this, there is no effect of blood donation on performance as measured by time to fatigue during an incremental test on a cycle ergometer.     

Skinfold thickness is related to cardiovascular autonomic control as assessed by heart rate variability and heart rate recovery

The purpose of this study was to determine if heart rate recovery (HRR) and heart rate variability (HRV) are related to maximal aerobic fitness and selected body composition measurements. Fifty men (age = 21.9 ± 3.0 years, height = 180.8 ± 7.2 cm, weight = 80.4 ± 9.1 kg, volunteered to participate in this study. For each subject, body mass index (BMI), waist circumference (WC), and the sum of skinfolds across the chest, abdomen, and thigh regions (SUMSF) were recorded. Heart rate variability (HRV) was assessed during a 5-minute period while the subjects rested in a supine position. The following frequency domain parameters of HRV were recorded: normalized high-frequency power (HFnu), and low-frequency to high-frequency power ratio (LF:HF). To determine maximal aerobic fitness (i.e., VO2max), each subject performed a maximal graded exercise test on a treadmill. Heart rate recovery was recorded 1 (HRR1) and 2 (HRR2) minutes during a cool-down period. Mean VO2max and BMI for all the subjects were 49.5 ± 7.5 ml·kg(-1)·min(-1) and 24.7 ± 2.2 kg·m(-2), respectively. Although VO2max, WC, and SUMSF was each significantly correlated to HRR and HRV, only SUMSF had a significant independent correlation to HRR1, HRR2, HFnu, LF:HF (p < 0.01). The results of the regression procedure showed that SUMSF accounted for the greatest variance in HRR1, HRR2, HFnu, and LF:HF (p < 0.01). The results of this study suggest that cardiovascular autonomic modulation is significantly related to maximal aerobic fitness and body composition. However, SUMSF appears to have the strongest independent relationship with HRR and HRV, compared to other body composition parameters and VO2max.     

Electromyographic activity and rate of muscle fatigue of the quadriceps femoris during cycling exercise in the severe domain

This study compared the activation pattern and the fatigue rate among the superficial muscles of the quadriceps femoris (QF) during severe cycling exercise. Peak oxygen consumption (VO(2)peak) and maximal accumulated oxygen Deficit (MAOD) were established by 10 well-trained male cyclists (27.5 ± 4.1 years, 71.0 ± 10.3 kg, 173.4 ± 6.6 cm, mean VO(2)peak 56.7 ± 4.4 ml·kg·min(-1), mean MAOD 5.7 ± 1.1 L). Muscle activity (electromyographic [EMG] signals) was obtained during the supramaximal constant workload test (MAOD) and expressed by root mean square (RMS) and median frequency (MF slope). The RMS of the QF, vastus lateralis (VL) and vastus medialis (VM) muscles were significantly higher than at the beginning after 75% of exercise duration, whereas for the rectus femoris (RF), this was observed after 50% of exercise duration (p ≤ 0.05). The slope of the MF was significantly higher in the RF, followed by the VL and VM (-3.13 ± 0.52 vs. -2.61 ± 0.62 vs. -1.81 ±0.56, respectively; p < 0.05). We conclude that RF may play an important role in limiting performance during severe cycling exercise.     

Effects of gradual-elastic compression stockings on running economy, kinematics, and performance in runners

We investigated the effect of gradual-elastic compression stockings (GCSs) on running economy (RE), kinematics, and performance in endurance runners. Sixteen endurance trained athletes (age: 34.73 ± 6.27 years; VO2max: 62.83 ± 9.03 ml·kg(-1)·min(-1); 38 minutes in 10 km; 1 hour 24 minutes in half marathon) performed in random order 4 bouts of 6 minutes at a recent half-marathon pace on a treadmill to evaluate RE with or without GCSs. Subsequently, 12 athletes were divided into 2 equal groups matched by their VO2max, and they performed a time limit test (T(lim)) on a treadmill at 105% of a recent 10-km pace with or without GCSs for evaluation of physiological responses and running kinematics. There were no significant differences in the RE test in all of the variables analyzed for the conditions, but a moderate reproducibility for some physiological responses was detected in the condition with GCSs. In the T(lim), the group that wore GCSs reached a lower % of maximum heart rate (HRmax) compared with the control group (96.00 ± 2.94 vs. 99.83 ± 0.40) (p = 0.01). Kinematics did not differ between conditions during the T(lim) (p > 0.05). There were improvement trends for time to fatigue (337 vs. 387 seconds; d = 0.32) and a lower VO2peak (≈53 vs. 62 ml·kg(-1)·min(-1); d = 1.19) that were detected with GCSs during the T(lim). These results indicate that GCSs reduce the % of HRmax reached during a test at competition pace. The lower reproducibility of the condition with GCSs perhaps suggests that athletes may possibly need an accommodation period for systematically experiencing the benefits of this garment, but this hypothesis should be further investigated.     

Maximal lactate steady-state independent of recovery period during intermittent protocol

Barbosa, LF, de Souza, MR, Corrêa Caritá, RA, Caputo, F, Denadai, BS, and Greco, CC. Maximal lactate steady-state independent of recovery period during intermittent protocol. J Strength Cond Res 25(12): 3385-3390, 2011-The purpose of this study was to analyze the effect of the measurement time for blood lactate concentration ([La]) determination on [La] (maximal lactate steady state [MLSS]) and workload (MLSS during intermittent protocols [MLSSwi]) at maximal lactate steady state determined using intermittent protocols. Nineteen trained male cyclists were divided into 2 groups, for the determination of MLSSwi using passive (VO(2)max = 58.1 ± 3.5 ml·kg·min; N = 9) or active recovery (VO(2)max = 60.3 ± 9.0 ml·kg·min; N = 10). They performed the following tests, in different days, on a cycle ergometer: (a) Incremental test until exhaustion to determine (VO(2)max and (b) 30-minute intermittent constant-workload tests (7 × 4 and 1 × 2 minutes, with 2-minute recovery) to determine MLSSwi and MLSS. Each group performed the intermittent tests with passive or active recovery. The MLSSwi was defined as the highest workload at which [La] increased by no more than 1 mmol·L between minutes 10 and 30 (T1) or minutes 14 and 44 (T2) of the protocol. The MLSS (Passive-T1: 5.89 ± 1.41 vs. T2: 5.61 ± 1.78 mmol·L) and MLSSwi (Passive-T1: 294.5 ± 31.8 vs. T2: 294.7 ± 32.2 W; Active-T1: 304.6 ± 23.0 vs. T2: 300.5 ± 23.9 W) were similar for both criteria. However, MLSS was lower in T2 (4.91 ± 1.91 mmol·L) when compared with in T1 (5.62 ± 1.83 mmol·L) using active recovery. We can conclude that the MLSSwi (passive and active conditions) was unchanged whether recovery periods were considered (T1) or not (T2) for the interpretation of [La] kinetics. In contrast, MLSS was lowered when considering the active recovery periods (T2). Thus, shorter intermittent protocols (i.e., T1) to determine MLSSwi may optimize time of the aerobic capacity evaluation of well-trained cyclists.     

Impact of protein coingestion on muscle protein synthesis during continuous endurance type exercise

This study investigates the impact of protein coingestion with carbohydrate on muscle protein synthesis during endurance type exercise. Twelve healthy male cyclists were studied during 2 h of fasted rest followed by 2 h of continuous cycling at 55% W(max). During exercise, subjects received either 1.0 g·kg(-1)·h(-1) carbohydrate (CHO) or 0.8 g·kg(-1)·h(-1) carbohydrate with 0.2 g·kg(-1)·h(-1) protein hydrolysate (CHO+PRO). Continuous intravenous infusions with l-[ring-(13)C(6)]phenylalanine and l-[ring-(2)H(2)]tyrosine were applied, and blood and muscle biopsies were collected to assess whole body protein turnover and muscle protein synthesis rates at rest and during exercise conditions. Protein coingestion stimulated whole body protein synthesis and oxidation rates during exercise by 22 ± 3 and 70 ± 17%, respectively (P < 0.01). Whole body protein breakdown rates did not differ between experiments. As a consequence, whole body net protein balance was slightly negative in CHO and positive in the CHO+PRO treatment (-4.9 ± 0.3 vs. 8.0 ± 0.3 μmol Phe·kg(-1)·h(-1), respectively, P < 0.01). Mixed muscle protein fractional synthetic rates (FSR) were higher during exercise compared with resting conditions (0.058 ± 0.006 vs. 0.035 ± 0.006%/h in CHO and 0.070 ± 0.011 vs. 0.038 ± 0.005%/h in the CHO+PRO treatment, respectively, P < 0.05). FSR during exercise did not differ between experiments (P = 0.46). We conclude that muscle protein synthesis is stimulated during continuous endurance type exercise activities when carbohydrate with or without protein is ingested. Protein coingestion does not further increase muscle protein synthesis rates during continuous endurance type exercise.     

Evaluation of the American College of Sports Medicine submaximal treadmill running test for predicting VO2max

The purpose of this study was to assess the validity of the American College of Sports Medicine's (ACSM's) submaximal treadmill running test in predicting VO2max. Twenty-one moderately well-trained men aged 18-34 years performed 1 maximal treadmill test to determine maximal oxygen uptake (M VO2max) and 2 submaximal treadmill tests using 4 stages of continuous submaximal exercise. Estimated VO2max was predicted by extrapolation to age-predicted maximal heart rate (HRmax) and calculated in 2 ways: using data from all submaximal stages between 110 b·min(-1) and 85% HRmax (P VO2max-All), and using data from the last 2 stages only (P VO2max-2). The measured VO2max was overestimated by 3% on average for the group but was not significantly different to predicted VO2max (1-way analysis of variance [ANOVA] p = 0.695; M VO2max = 53.01 ± 5.38; P VO2max-All = 54.27 ± 7.16; P VO2max-2 = 54.99 ± 7.69 ml·kg(-1)·min(-1)), although M VO2max was not overestimated in all the participants--it was underestimated in 30% of observations. Pearson's correlation, standard error of estimate (SEE), and total error (E) between measured and predicted VO2max were r = 0.646, 4.35, 4.08 ml·kg(-1)·min(-1) (P VO2max-All) and r = 0.642, 4.21, 3.98 ml·kg(-1)·min(-1) (P VO2max-2) indicating that the accuracy in prediction (error) was very similar whether using P VO2max-All or P VO2max-2, with up to 70% of the participants predicted scores within 1 SEE (～4 ml·kg(-1)·min(-1)) of M VO2max. In conclusion, the ACSM equation provides a reasonably good estimation of VO2max with no difference in predictive accuracy between P VO2max-2 and P VO2max-All, and hence, either approach may be equally useful in tracking an individual's aerobic fitness over time. However, if a precise knowledge of VO2max is required, then it is recommended that this be measured directly.     

Predicting maximal aerobic capacity (VO2max) from the critical velocity test in female collegiate rowers

The objective of this study was to examine the relationship between the critical velocity (CV) test and maximal oxygen consumption (VO2max) and develop a regression equation to predict VO2max based on the CV test in female collegiate rowers. Thirty-five female (mean ± SD; age, 19.38 ± 1.3 years; height, 170.27 ± 6.07 cm; body mass, 69.58 ± 0.3 1 kg) collegiate rowers performed 2 incremental VO2max tests to volitional exhaustion on a Concept II Model D rowing ergometer to determine VO2max. After a 72-hour rest period, each rower completed 4 time trials at varying distances for the determination of CV and anaerobic rowing capacity (ARC). A positive correlation was observed between CV and absolute VO2max (r = 0.775, p < 0.001) and ARC and absolute VO2max (r = 0.414, p = 0.040). Based on the significant correlation analysis, a linear regression equation was developed to predict the absolute VO2max from CV and ARC (absolute VO2max = 1.579[CV] + 0.008[ARC] - 3.838; standard error of the estimate [SEE] = 0.192 L·min(-1)). Cross validation analyses were performed using an independent sample of 10 rowers. There was no significant difference between the mean predicted VO2max (3.02 L·min(-1)) and the observed VO2max (3.10 L·min(-1)). The constant error, SEE and validity coefficient (r) were 0.076 L·min(-1), 0.144 L·min(-1), and 0.72, respectively. The total error value was 0.155 L·min(-1). The positive relationship between CV, ARC, and VO2max suggests that the CV test may be a practical alternative to measuring the maximal oxygen uptake in the absence of a metabolic cart. Additional studies are needed to validate the regression equation using a larger sample size and different populations (junior- and senior-level female rowers) and to determine the accuracy of the equation in tracking changes after a training intervention.     

Muscle cellular properties in the ice hockey player: a model for investigating overtraining?

In this study, we hypothesized that athletes involved in 5-6 months of sprint-type training would display higher levels of proteins and processes involved in muscle energy supply and utilization. Tissue was sampled from the vastus lateralis of 13 elite ice hockey players (peak oxygen consumption = 51.8 ± 1.3 mL·kg(-1)·min(-1); mean ± standard error) at the end of a season (POST) and compared with samples from 8 controls (peak oxygen consumption = 45.5 ± 1.4 mL·kg(-1)·min(-1)) (CON). Compared with CON, higher activities were observed in POST (p < 0.05) only for succinic dehydrogenase (3.32 ± 0.16 mol·(mg protein)(-1)·min(-1) vs. 4.10 ± 0.11 mol·(mg protein)(-1)·min(-1)) and hexokinase (0.73 ± 0.05 mol·(mg protein)(-1)·min(-1) vs. 0.90 ± 0.05mol·(mg protein)(-1)·min(-1)) but not for phosphorylase, phosphofructokinase, and creatine phosphokinase. No differences were found in Na(+),K(+)-ATPase concentration (β(max): 262 ± 36 pmol·(g wet weight)(-1) vs. 275 ± 27 pmol·(g wet weight)(-1)) and the maximal activity of the sarcoplasmic reticulum Ca(2+)-ATPase (98.1 ± 6.1 μmol·(g protein)(-1)·min(-1) vs. 102 ± 3.3 μmol·(g protein)(-1)·min(-1)). Cross-sectional area was lower (p < 0.05) in POST but only for the type IIA fibres (6312 ± 684 μm(2) vs. 5512 ± 335 μm(2)), while the number of capillary counts per fibre and the capillary to fibre area ratio were generally higher (p < 0.05). These findings suggest that elite trained ice hockey players display elevations only in support of glucose-based aerobic metabolism that occur in the absence of alterations in excitation-contraction processes.