Maximal strength training in patients with Parkinson's disease: impact on efferent neural drive, force-generating capacity, and functional performance.

Parkinson's disease (PD) is characterized by progressive neurological deterioration, typically accompanied by reductions in skeletal muscle force-generating capacity (FGC) and functional performance. Physical activity has the potential to counteract this debilitating outcome, however, it is elusive if high-intensity strength training included in conventional treatment may improve results. Therefore, we randomly assigned 22 PD patients (74 ± 9 yr) to conventional rehabilitation with or without maximal strength training (MST) performed as leg press and chest press at ~90% of one repetition maximum (1RM), five times per week for 4 wk. FGC, physical performance, and efferent neural drive assessed as evoked potentials (V-wave normalized to M-wave in m. soleus) were measured following training. Results revealed that only MST improved 1RM leg press (101 ± 23 to 118 ± 18 kg) and chest press (36 ± 15 to 41 ± 15 kg), plantar flexion maximal voluntary contraction (235 ± 125 to 293 ± 158 N·m), and rate of force development (373 ± 345 to 495 ± 446 N·m·s-1; all P < 0.05; different from controls P < 0.05). FGC improvements were accompanied by an increased efferent neural drive to maximally contracting musculature (V-to-M ratio: 0.17 ± 0.12 to 0.24 ± 0.15; P < 0.05; different from controls P < 0.05), improved physical performance (stair climbing: 21.0 ± 9.2 to 14.4 ± 5.2 s; timed up and go: 7.8 ± 3.3 to 6.2 ± 2.5 s; both P < 0.05), and self-perceived improvement in health (3.1 ± 0.5 to 2.6 ± 0.9) and social activities functioning (2.2 ± 1.0 to 1.5 ± 1.1; both P < 0.05). No changes were observed in the control group. In conclusion, this study shows that MST improves FGC, neuromuscular function, and functional performance and advocates that high-intensity strength training should be implemented as an adjunct therapy in the treatment of PD patients.NEW & NOTEWORTHY This randomized, controlled trial documents that supervised high-intensity strength training improves efferent neural drive, maximal muscle strength, rate of force development, and functional performance in patients with Parkinson's disease (PD). In contrast, no differences were observed in these outcome variables in patients receiving conventional treatment consisting of recreational physical activity with low-to-medium intensity. Consequently, this study advocates that high-intensity strength training should be implemented in the clinical treatment of PD patients.

Blood flow regulation and oxygen uptake during high-intensity forearm exercise.

The vascular strain is very high during heavy handgrip exercise, but the intensity and kinetics to reach peak blood flow, and peak oxygen uptake, are uncertain. We included 9 young (25 ± 2 yr) healthy males to evaluate blood flow and oxygen uptake responses during continuous dynamic handgrip exercise with increasing intensity. Blood flow was measured using Doppler-ultrasound, and venous blood was drawn from a deep forearm vein to determine arteriovenous oxygen difference (a-vO2diff) during 6-min bouts of 60, 80, and 100% of maximal work rate (WRmax), respectively. Blood flow and oxygen uptake increased (P < 0.05) from 60%WRmax [557 ± 177(SD) ml/min; 56.0 ± 21.6 ml/min] to 80%WRmax (679 ± 190 ml/min; 70.6 ± 24.8 ml/min), but no change was seen from 80%WRmax to 100%WRmax Blood velocity (49.5 ± 11.5 to 58.1 ± 11.6 cm/s) and brachial diameter (0.49 ± 0.05 to 0.50 ± 0.06 cm) showed concomitant increases (P < 0.05) with blood flow from 60% to 80%WRmax, whereas no differences were observed in a-vO2diff Shear rate also increased (P < 0.05) from 60% (822 ± 196 s-1) to 80% (951 ± 234 s-1) of WRmax The mean response time (MRT) was slower (P < 0.05) for blood flow (60%WRmax 50 ± 22 s; 80%WRmax 51 ± 20 s; 100%WRmax 51 ± 23 s) than a-vO2diff (60%WRmax 29 ± 9 s; 80%WRmax 29 ± 5 s; 100%WRmax 20 ± 5 s), but not different from oxygen uptake (60%WRmax 44 ± 25 s; 80%WRmax 43 ± 14 s; 100%WRmax 41 ± 32 s). No differences were observed in MRT for blood flow or oxygen uptake with increased exercise intensity. In conclusion, when approaching maximal intensity, oxygen uptake appeared to reach a critical level at ~80% of WRmax and be regulated by blood flow. This implies that high, but not maximal, exercise intensity may be an optimal stimulus for shear stress-induced small muscle mass training adaptations.NEW & NOTEWORTHY This study evaluated blood flow regulation and oxygen uptake during small muscle mass forearm exercise with high to maximal intensity. Despite utilizing only a fraction of cardiac output, blood flow reached a plateau at 80% of maximal work rate and regulated peak oxygen uptake. Furthermore, the results revealed that muscle contractions dictated bulk oxygen delivery and yielded three times higher peak blood flow in the relaxation phase compared with mean values.

The effect from maximal bench press strength training on work economy during wheelchair propulsion in men with spinal cord injury.

OBJECTIVE: To assess the effect from maximal bench press strength training (MST) on wheelchair propulsion work economy (WE). STUDY DESIGN: Pretest-posttest case-control group design. SETTING: St Olavs Hospital, Trondheim, Norway. METHODS: Seventeen male individuals with spinal cord injury (SCI) paraplegia were allocated to either MST bench press (n=11) or the control group (CG) (n=7). The MST group trained bench press three times per week, for 6 weeks, starting at 85-95% of their pretest bench press one-repetition maximum (1RM). For calculation of WE during wheelchair propulsion, oxygen uptake (VO2) measurements were collected during wheelchair ergometry (WCE) at submaximal workload of 50 W. Similarly, peak oxygen uptake (VO2peak) and peak power output (W) were measured during WCE. RESULTS: Individuals in the MST regimen significantly improved WE compared with the CG by 17.3 % (mean between-group differences: 95% confidence interval) of 2.63 ml kg-1 min-1: (-4.34, -0.91) (P=0.007). Between pretest and posttest, the increase in bench press 1RM was by 17% higher in the MST group compared with the CG. At peak testing, the MST group generated significantly higher peak power compared with the CG. All other physiological variables were comparable within and between groups. CONCLUSIONS: A 6-week MST bench press regimen significantly improved WE during wheelchair propulsion at 50 W workload. These preliminary data support a possible beneficial role for MST to reduce the energy cost of wheelchair propulsion for SCI individuals.

Comparison of thoracic bioimpedance with acetylene uptake for measuring cardiac output.

UNLABELLED: Cardiac output is shown to be a key determinant for oxygen transport, performance and health. Reliable and accurate non-invasive measurements of cardiac output, especially during exercise, are therefore of importance. The present study compared a new thoracic bioimpedance method with the established single-breath acetylene uptake method. We assessed cardiac output in 20 (24±4 years.) moderately trained males, at rest and during cycling. Both methods showed good test-retest reliabilities with ±2 SD limits of agreement of 3.67 and -4.50 L ∙ min(-1) (thoracic bioimpedance) and 4.46 and -5.69 L ∙ min(-1) (single breath), respectively. When thoracic bioimpedance was compared with single breath, the ±2 SD limits of agreement were poor (-6.05 and 9.57 L ∙ min(-1)). Thoracic bioimpedance displayed significantly lower (p<0.05) absolute cardiac output values than single breath, and the cardiac output-oxygen consumption slopes (y=5.7x+5.5 (single breath) and y=5.0x+5.0 (thoracic bioimpedance) tended (p=0.08) to show less increase for thoracic bioimpedance. CONCLUSIONS: Results from the single-breath method are in line with previous findings, showing a good reliability. Although thoracic bioimpedance showed a similar reliability as the single-breath method, and is easier to use, the agreement with single breath was poor, and thoracic bioimpedance seems not to be able to replace it.

Structural brain changes after 4 wk of unilateral strength training of the lower limb.

Strength training enhances muscular strength and neural drive, but the underlying neuronal mechanisms remain unclear. This study used magnetic resonance imaging (MRI) to identify possible changes in corticospinal tract (CST) microstructure, cortical activation, and subcortical structure volumes following unilateral strength training of the plantar flexors. Mechanisms underlying cross-education of strength in the untrained leg were also investigated. Young, healthy adult volunteers were assigned to training (n = 12) or control (n = 9) groups. The 4 wk of training consisted of 16 sessions of 36 unilateral isometric plantar flexions. Maximum voluntary isometric contraction torque was tested pre- and posttraining. MRI investigation included a T1-weighted scan, diffusion tensor imaging and functional MRI. Probabilistic fiber tracking of the CST was performed on the diffusion tensor imaging images using a two-regions-of-interest approach. Fractional anisotropy and mean diffusivity were calculated for the left and right CST in each individual before and after training. Standard functional MRI analyses and volumetric analyses of subcortical structures were also performed. Maximum voluntary isometric contraction significantly increased in both the trained and untrained legs of the training group, but not the control group. A significant decrease in mean diffusivity was found in the left CST following strength training of the right leg. No significant changes were detected in the right CST. No significant changes in cortical activation were observed following training. A significant reduction in left putamen volume was found after training. This study provides the first evidence for strength training-related changes in white matter and putamen in the healthy adult brain.

Stroke volume does not plateau in female endurance athletes.

It has been a long-lasting debate whether the heart's stroke volume (SV) increases at high aerobic intensities or plateau. Further, sex and level of aerobic power are shown to influence the response. The purpose of this study was to investigate the SV at increasing intensities in elite female athletes and moderately trained females. 13 elite athletes and 11 moderately trained controls with maximal oxygen consumption (VO(2max)) of 67.1 ± 6.1 and 49.5 ± 2.3 mL ∙ min (- 1) ∙ kg (- 1), respectively, were recruited. SV was measured at rest, and running on a treadmill at 40%, 60%, 80% and 100% of VO(2max) using the single breath acetylene uptake (SB) technique. Both groups showed a significant (p<0.05) increase in SV from 40% of VO2max to VO(2max), with increases from 105.3 ± 19.0 to 129.1 ± 16.3 mL∙ beat(-1) for the elite females and from 68.7 ± 21.7 to 82.7 ± 14.0 mL ∙ beat (- 1) for the moderately trained. No differences were observed between groups in these increases, but the elite athletes displayed a larger (p<0.05) SV at all intensities. It is concluded that the SV increases at high aerobic intensities both in elite athlete females and moderately trained females.

Effect of leg vascular occlusion on arm cycling peak oxygen uptake in spinal cord-injured individuals.

STUDY DESIGN: Cross-sectional single-subject design. OBJECTIVES: To determine whether leg vascular occlusion (LEVO) augment arm cycling (ACE) peak oxygen uptake in spinal cord-injured individuals. SETTING: University Hospital, Norway. METHODS: Fifteen individuals with C(4) to T(12) spinal cord injury (SCI) were recruited and divided into two groups: injury above (SCI-high, n=8) or below (SCI-low, n=7) the T(6) level. Peak oxygen uptake (VO(2peak)) was measured during (1) ACE combined with LEVO, (2) ACE alone and (3) ACE combined with functional electrical stimulation cycling (FES hybrid cycling). RESULTS: In the SCI-high group, VO(2peak) and peak Watt during ACE with LEVO were higher than ACE alone: 20.0 (±5.0) versus 17.6 (±5.0) ml kg(-1) min(-1) (P=0.006), and 72.5(±32) versus 80.0 (±34) Watt (P=0.016), respectively. However, FES hybrid cycling VO(2peak) was significantly higher than ACE with LEVO: 24.4 (±4.1) versus 20.0 (±5.0) ml kg(-1) min(-1) (P=0.006). In the SCI-low group, there was no difference in VO(2peak) and related parameters between the three modalities. CONCLUSIONS: For spinal cord-injured individuals with injury level above T(6) (high) in the present study, LEVO combined with ACE augment VO(2peak). However, this acute increase in VO(2peak) was lower than when FES cycling was combined with ACE. These findings may have future implications for exercise prescription for spinal cord-injured individuals.

Strength and endurance in elite football players.

We aimed to improve the physical capacity of a top-level elite football team during its pre-season by implementing a maximal strength and high-intensity endurance training program. 21 first league elite football players (20-31 yrs, height 171-194 cm, mass 58.8-88.1 kg) having recently participated in the UEFA Champions' League, took part in the study. Aerobic interval-training at 90-95% of maximal heart rate and half-squats strength training with maximum loads in 4 repetitions × 4 sets were performed concurrently twice a week for 8 weeks. The players were not familiar with maximal strength training as part of their regular program. Maximal oxygen uptake (VO(2max)) increased 8.6% (1.7-16.6) (p<0.001), from 60.5 (51.7-67.1) to 65.7 (58.0-74.5) mL · kg (-1) · min (-1) whereas half-squat one repetition maximum increased 51.7% (13.3-135.3) (p<0.001), from 116 (85-150) to 176 (160-210) kg. The 10-m sprint time also improved by 0.06 s (0.02-0.16) (p<0.001); while counter movement jump improved 3.0 cm (0.1-6.2) (p<0.001), following the training program. The concurrent strength and endurance training program together with regular football training resulted in considerable improvement of the players' physical capacity and so may be successfully introduced to elite football players.

Concurrent strength and endurance training improves physical capacity in patients with peripheral arterial disease.

Peripheral arterial disease (PAD) patients suffer from reduced blood flow to the lower extremities, which causes impaired walking ability. Plantar flexion (PF) endurance training and maximal strength training (MST) induce distinct types of improvements in walking ability in PAD. However, the combined effects of both exercises are still not explored in these patients. This study examined whether concurrent MST and PF training would induce similar training responses as each training mode alone. Ten patients with PAD underwent 8 weeks of concurrent leg press MST and PF training, three times a week. The reference group (n=10) received recommended exercise guidelines. The training group improved treadmill peak oxygen consumption and incremental protocol time to exhaustion with 12.7 ± 7.7% and 12.6 ± 13.2%. Leg press maximal strength and rate of force development improved with 38.3 ± 3.1% and 140.1 ± 40.3%, respectively, along with a 5.2 ± 6.2% within group work economy improvement. No changes appeared in the reference group. Compared with previous studies, concurrent MST and PF training appear to induce similar training responses in PAD patients as when each training mode is executed alone, and without any adverse effects.

Interval and strength training in CAD patients.

This study sought to study the effect of high intensity aerobic interval endurance training on peak stroke volume and maximal strength training on mechanical efficiency in coronary artery disease (CAD) patients. 8 CAD patients (age 61.4 ± 3.7 years) trained 30 interval training sessions with 4 × 4 min intervals at 85-95% of peak heart rate while 10 CAD patients (age 66.5 ± 5.5 years) trained 24 sessions of maximal horizontal leg press. In the interval training group peak stroke volume increased significantly by 23% from 94.1 ± 23.0 mL · beat (-1) to 115.8 ± 22.4 mL · beat (-1) (p<0.05). Peak oxygen uptake increased significantly by 17% from 27.2 ± 4.5 mL · kg (-1) · min (-1) to 31.8 ± 5.0 mL · kg (-1) min (-1) (p<0.05) in the same group. In contrast, there was no such exercise training-induced change in peak stroke volume or peak oxygen uptake in the maximal strength training group, despite a 35% improvement in sub maximal walking performance.

Maximal strength training improves walking performance in peripheral arterial disease patients.

Peripheral arterial disease (PAD) patients have reduced muscle strength and impaired walking ability. The aim of this study was to examine the effects of maximal strength training (MST) on walking economy and walking performance in PAD patients. Ten patients with mild to moderate-severe claudication, classified as Fontaine stage II PAD and with functional limitations from intermittent claudication were recruited and went through an 8-week control period followed by an 8-week, three times a week, MST period. The patients performed four sets of five repetitions dynamic leg press with emphasis on maximal mobilization of force in the concentric action and with a progressive adjusted intensity corresponding to 85-90% of one repetition maximum (1 RM). After the MST period, leg press 1 RM significantly increased by 35.0 ± 10.8 kg (31.3%). Dynamic rate of force development, measured on a force plate installed on the leg press, increased by 1424 ± 1217 N/s (102.7%). The strength improvements led to a significant increase in walking economy of 9.7% when walking horizontally, and to a significant increase in walking performance of 13.6% measured on an incremental treadmill test to exhaustion. No changes were apparent after the control period. No changes in body mass or peak oxygen uptake were observed. MST increases strength in Fontaine stage II PAD patients and leads to improved walking economy. These results suggest that application of MST could accompany aerobic endurance training as a part of the treatment of PAD patients with mild to moderate-severe claudication.

Hyperoxic interval training in chronic obstructive pulmonary disease patients with oxygen desaturation at peak exercise.

High-intensity work might not be preserved in chronic obstructive pulmonary disease (COPD) during whole-body exercise due to ventilatory limitations that exceed metabolic limitations, resulting in reduced training adaptations. The purpose of the present study was to address the hyperoxic effect during training and testing in COPD patients with hypoxemia at peak exercise. Six COPD and eight coronary artery disease (CAD) patients completed 24 aerobic high-intensity interval training sessions, 4x4 min in hyperoxia at 85-95% of the peak heart rate and peak exercise tested in normoxia and hyperoxia pre- and post-training. VO2peak increased in the COPD group by 19% (13-31%) and in the CAD group by 15% (7-29%), [0.98(0.68-1.52)-1.17(0.89-1.78) and 2.11(1.57-2.64)-2.44(1.92-3.39) L/min], respectively. VO2peak was higher in hyperoxia at pre- and post-test (1.22(0.80-1.87) and 1.37(1.01-1.94) L/min) in the COPD group. Work economy improved by 10% in both groups. Quality of life improved in the COPD group in terms of physical and mental health status by 24% and 35%. Hyperoxic aerobic high-intensity interval training in COPD patients with hypoxemia at peak exercise increases VO2peak, peak workload, work economy and quality of life. Acute hyperoxia increases VO2peak, peak workload at pre- and post-test compared with normoxia in the COPD patients, indicating an oxygen supply limitation to VO2peak.

Aerobic high intensity one-legged interval cycling improves peak oxygen uptake in chronic obstructive pulmonary disease patients; no additional effect from hyperoxia.

The aim of the present study was to investigate whether hyperoxic aerobic high intensity one-legged interval cycling improves peak oxygen uptake (V O (2peak)) compared to normoxic training in patients with severe chronic obstructive pulmonary disease, and to evaluate the acute effect of hyperoxia during one- and two-legged peak exercise testing. Twelve COPD patients were recruited to perform 3 training sessions per week for 8 weeks in hyperoxia (n=7) or normoxia (n=5). Each leg was trained 4x4 min at 85-95% of the one-legged peak heart rate. One-legged V O (2peak) increased in the hyperoxia and normoxia training groups by 24 and 15% (16.1(13.2)-20.0(11.3) and 17.4(15.1)-20.0(6.7) mL.kg (-1).min (-1)) respectively. The corresponding increases in V O (2peak) during two-legged testing were 14% in both groups (20.1(11.5)-22.9(10.6) and 18.8(8.5)-21.4(7.3) mL.kg (-1).min (-1)). There were no differences between groups from pre- to post-training. Nor were there any differences between acute hyperoxia and normoxia at the pre- or post-peak exercise test. One-legged aerobic high intensity interval cycling significantly increases V O (2peak) in COPD patients. However, breathing supplemental oxygen during training or testing does not appear to improve V O (2peak) above the level attained by breathing ambient air.

Maximal strength training restores walking mechanical efficiency in heart patients.

The purpose of this study was to investigate whether maximal strength leg press training improves walking mechanical efficiency in coronary artery disease patients. Ten coronary artery disease patients trained 24 sessions of horizontal leg press. Each training session consisted of 4 sets with 4 repetitions of maximal mobilization of concentric force to exhaustion. Seven healthy age matched subjects served as time controls. Maximal strength training improved walking mechanical efficiency (i.e. the oxygen cost to generate a given work load) by 35% (p=0.007) in coronary artery disease patients (from 18+/-4% at pre test to 25+/-6% at post test), and restored walking efficiency to the level of the healthy age matched controls ( approximately 25%). Strength training further improved one repetition maximum from 138+/-24 to 198+/-24 kg (44%) (p=0.000) and rate of force development by 85% (p=0.001), with no change in the control group. Maximal strength leg press training restores walking mechanical efficiency and significantly improves one repetition maximum and rate of force development in coronary artery disease patients after 24 training sessions each lasting only 20 min.

Strength and endurance differences between elite and junior elite ice hockey players. The importance of allometric scaling.

The aim of this study was to investigate differences in strength and endurance between elite and elite junior ice hockey players. Participants included 18 elite players and 21 junior elite male players (24.2 +/- 4.7 vs. 17.6 +/- 0.9 years of age, 84.2 +/- 8.1 vs. 72.3 +/- 6.0 kg body mass (p < 0.01), 179.9 +/- 6.1 vs. 179.0 +/- 7.0 cm). Absolute maximal oxygen uptake was significantly higher in elite than junior players (4.8 vs. 4.2 L x min(-1), p < 0.01), but relative expressions, including allometric scaling, eliminated the difference. Elite players lifted significantly more weight than juniors in 1 repetition maximum squats (200.0 +/- 28.9 vs. 140.3 +/- 19.5 kg, p < 0.01) and in bench press (100.8 +/- 12.8 vs. 75.3 +/- 12.8 kg, p < 0.01). Elite players also ran significantly faster in the 10 m sprint (1.80 +/- 0.07 vs. 1.88 +/- 0.08 s, p < 0.01), and had greater jumping height (27.2 +/- 3.2 vs. 20.5 +/- 3.0 cm, p < 0.01) and peak force (2336.4 +/- 219.9 vs. 2011.9 +/- 180.1 N, p < 0.01) when holding 50 extra kg. No differences were found for the 40 m sprint or for the rate of force development in jumping. This study revealed that the main differences between elite and junior ice hockey players at a high performance level seem to be in strength and body mass. The results therefore identify important factors for juniors to improve in the transition phase from junior to elite level.

Lactate threshold responses to a season of professional British youth soccer.

OBJECTIVE: To examine the changes in aerobic endurance performance of professional youth soccer players throughout the soccer season. METHODS: Nine youth soccer players were tested at six different time points throughout the soccer season by sub-maximal blood lactate assessment, using an incremental treadmill protocol. Whole blood lactate concentration and heart frequency (Hf) were determined at each exercise stage. Running velocities at the first lactate inflection point (v-T(lac)) and at a blood lactate concentration of 4 mmol l(-1) (v-4mM) were determined. RESULTS: Running velocity at the two lactate thresholds increased from the start of pre-season training to the early weeks of the competitive season, from 11.67 (0.29) to 12.96 (0.28) km h(-1) for v-T(lac), and from 13.62 (0.25) to 14.67 (0.24) km h(-1) for v-4mM (p<0.001). However, v-T(lac )and v-4mM when expressed relative to maximum heart frequency (Hf(max)) remained unchanged. The Hf to blood lactate concentration relationship was unchanged after the pre-season training period. The two expressions of lactate threshold did not reveal differences between each other. CONCLUSION: Running velocity at v-T(lac )and v-4mM increased significantly over the pre-season period, but v-T(lac )and v-4mM were unchanged when expressed relative to Hf(max). This finding may indicate that increased endurance performance may be mainly attributable to alterations in Vo(2max). Although lactate assessment of soccer players is useful for determining endurance training adaptations in soccer players, additional assessment of the other two determinants of endurance performance (Vo(2max) and running economy) may provide more useful information for determining physiological adaptations resulting from soccer training and training interventions.

Physiological adaptations to soccer specific endurance training in professional youth soccer players.

BACKGROUND: Improved oxygen uptake improves soccer performance as regards distance covered, involvements with the ball, and number of sprints. Large improvements in oxygen uptake have been shown using interval running. A similar physiological load arising from interval running could be obtained using the soccer ball in training. OBJECTIVES: The main aim was to study physiological adaptations to a 10 week high intensity aerobic interval training program performed by professional youth soccer players, using a soccer specific ball dribbling track. METHODS: Eleven youth soccer players with a mean (SD) age of 16.9 (0.4) years performed high intensity aerobic interval training sessions twice per week for 10 weeks in addition to normal soccer training. The specific aerobic training consisted of four sets of 4 min work periods dribbling a soccer ball around a specially designed track at 90-95% of maximal heart frequency, with a 3 min recovery jog at 70% of maximal heart frequency between intervals. RESULTS: Mean VO2max improved significantly from 63.4 (5.6) to 69.8 (6.6) ml kg(-1) min(-1), or 183.3 (13.2) to 201.5 (16.2) ml kg(-0.75) min(-1) (p<0.001). Squat jump and counter movement jump height increased significantly from 37.7 (6.2) to 40.3 (6.1) cm and 52.0 (4.0) to 53.4 (4.2) cm, respectively (p<0.05). No significant changes in body mass, running economy, rate of force development, or 10 m sprint times occurred. CONCLUSION: Performing high intensity 4 min intervals dribbling a soccer ball around a specially designed track together with regular soccer training is effective for improving the VO2max of soccer players, with no negative interference effects on strength, jumping ability, and sprinting performance.

Strong correlation of maximal squat strength with sprint performance and vertical jump height in elite soccer players.

BACKGROUND: A high level of strength is inherent in elite soccer play, but the relation between maximal strength and sprint and jumping performance has not been studied thoroughly. OBJECTIVE: To determine whether maximal strength correlates with sprint and vertical jump height in elite male soccer players. METHODS: Seventeen international male soccer players (mean (SD) age 25.8 (2.9) years, height 177.3 (4.1) cm, weight 76.5 (7.6) kg, and maximal oxygen uptake 65.7 (4.3) ml/kg/min) were tested for maximal strength in half squats and sprinting ability (0-30 m and 10 m shuttle run sprint) and vertical jumping height. RESULT: There was a strong correlation between maximal strength in half squats and sprint performance and jumping height. CONCLUSIONS: Maximal strength in half squats determines sprint performance and jumping height in high level soccer players. High squat strength did not imply reduced maximal oxygen consumption. Elite soccer players should focus on maximal strength training, with emphasis on maximal mobilisation of concentric movements, which may improve their sprinting and jumping performance.

Soccer specific testing of maximal oxygen uptake.

AIM: Endurance capacity in soccer players is important. A soccer specific test for direct measurement of maximal oxygen uptake does, however, not exist. The aim of this study was to evaluate maximal oxygen uptake in a soccer specific field test, compared to treadmill running. METHODS: Ten male soccer players (age 21.9+/-3.0 years, body mass 73.3+/-9.5 kg, height 179.9+/-4.7 cm) participated in the study, and 5 endurance trained men (age 24.9+/-1.8 years, body mass 81.5+/-3.7 kg, height 185.6+/-3.1 cm) took part in a comparison of the portable and the stationary metabolic test systems. The soccer players accomplished a treadmill test and a soccer specific field test containing dribbling, repetitive jumping, accelerations, decelerations, turning and backwards running. RESULTS: Maximal oxygen uptake was similar in field (5.0+/-0.5 L x min(-1)) and laboratory (5.1+/-0.7 L x min(-1)) tests, as were maximal heart rate, maximal breathing frequency, respiratory exchange ratio and oxygen pulse. Maximal ventilation was 5.4% higher at maximal oxygen uptake during treadmill running. CONCLUSION: These findings show that testing of maximal oxygen uptake during soccer specific testing gives similar results as during treadmill running, and therefore serves as a valid test of maximal oxygen uptake in soccer players.

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.