Neuromuscular adaptations to concurrent strength and endurance training

Department of Orthopedics, University of Wisconsin-Madison, Madison, WI 53706, USA.
Medicine &amp Science in Sports &amp Exercise (Impact Factor: 3.98). 03/2002; 34(3):511-9. DOI: 10.1097/00005768-200203000-00019
Source: PubMed


The purpose of this study was to examine muscle morphological and neural activation adaptations resulting from the interaction between concurrent strength and endurance training.
Thirty sedentary healthy male subjects were randomly assigned to one of three training groups that performed 10 wk of 3-d x wk(-1) high-intensity strength training (S), cycle endurance training (E), or concurrent strength and endurance training (CC). Strength, quadriceps-muscle biopsies, computed tomography scans at mid-thigh, and surface electromyogram (EMG) assessments were made before and after training.
S and CC groups demonstrated similar increases (P < 0.0001) in both thigh extensor (12 and 14%) and flexor/adductor (7 and 6%) muscle areas. Type II myofiber areas similarly increased (P < 0.002) in both S (24%) and CC (28%) groups, whereas the increase (P < 0.004) in Type I area with S training (19%) was also similar to the nonsignificant (P = 0.041) increase with CC training (13%). Significant increases (P < 0.005) in maximal isometric knee-extension torque were accompanied by nonsignificant (P <or= 0.07) increases in root mean squared EMG amplitude of the quadriceps musculature for both S and C groups. No changes (P > 0.38) in the EMG/torque relation across 20 to 100% maximal voluntary contractions occurred in any group. A small 3% increase (P < 0.01) in thigh extensor area was the only change in any of the above variables with E training.
Findings indicate 3-d x wk(-1) concurrent performance of both strength and endurance training does not impair adaptations in strength, muscle hypertrophy, and neural activation induced by strength training alone. Results provide a physiological basis to support several performance studies that consistently indicate 3-d x wk(-1) concurrent training does not impair strength development over the short term.

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    • "Some studies have shown that a high volume of concurrent training might impair the hypertrophy of type I fibers (Kraemer et al. 1995; Bell et al. 1997, 2000; Putman et al. 2004). Nevertheless, studies using imaging techniques to evaluate muscle hypertrophy have shown no differences in the magnitude of increase in muscle size between strength and concurrent groups in young (McCarthy et al. 2002; Häkkinen et al. 2003; Izquierdo et al. 2005), as well in elderly untrained subjects (Izquierdo et al. 2004; Sillampää et al. 2008; Karavirta et al. 2011). "

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    • "Regarding endurance adaptations, several studies have shown that there are no differences in the magnitude of cardiorespiratory adaptations when endurance training is performed alone or combined with strength training (Bell et al., 2000; McCarthy et al., 2002). However, Chtara et al. (2005) observed that performance of strength prior to endurance training resulted in lower enhancements in maximal endurance performed compared with the inverse order, which was justified as a consequence of fatigue resulting from strength training. "
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    ABSTRACT: This study aimed to investigate the acute effects of two strength-training protocols on the neuromuscular and cardiorespiratory responses during endurance exercise. Thirteen young males (23.2 ± 1.6 years old) participated in this study. The hypertrophic strength-training protocol was composed of 6 sets of 8 squats at 75% of maximal dynamic strength. The plyometric strength-training protocol was composed of 6 sets of 8 jumps performed with the body weight as the workload. Endurance exercise was performed on a cycle ergometer at a power corresponding to the second ventilatory threshold until exhaustion. Before and after each protocol, a maximal voluntary contraction was performed, and the rate of force development and electromyographic parameters were assessed. After the hypertrophic strength-training and plyometric strength-training protocol, significant decreases were observed in the maximal voluntary contraction and rate of force development, whereas no changes were observed in the electromyographic parameters. Oxygen uptake and a heart rate during endurance exercise were not significantly different among the protocols. However, the time-to-exhaustion was significantly higher during endurance exercise alone than when performed after hypertrophic strength-training or plyometric strength-training (p <0.05). These results suggest that endurance performance may be impaired when preceded by strength-training, with no oxygen uptake or heart rate changes during the exercise.
    Journal of Human Kinetics 12/2014; 442014(1):171-181. DOI:10.2478/hukin-2014-0123 · 1.03 Impact Factor
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    • "That being said, the present increase in lean mass is in agreement with the observation of 3% increase in lean body mass in elite cyclists (Aagaard et al. 2011), and a 4.5% increase in thigh muscle cross-sectional area has been observed in well-trained cyclists (Rønnestad et al. 2010a) due to concurrent strength and endurance training. These minor gains are substantially lower than the ~9-11% increase in cross-sectional area observed in studies employing similar strength training, but without endurance training (Aagaard et al. 2001; McCarthy et al. 2002; Rønnestad et al. 2012a). In the present study, both groups demonstrated a small ~1 kg increase in total body weight from pre-to post-testing. "
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    ABSTRACT: The purpose was to investigate the effect of 25 weeks heavy strength training in young elite cyclists. Nine cyclists performed endurance training and heavy strength training (ES) while seven cyclists performed endurance training only (E). ES, but not E, resulted in increases in isometric half squat performance, lean lower body mass, peak power output during Wingate test, peak aerobic power output (Wmax), power output at 4 mmol L−1 [la−], mean power output during 40-min all-out trial, and earlier occurrence of peak torque during the pedal stroke (P < 0.05). ES achieved superior improvements in Wmax and mean power output during 40-min all-out trial compared with E (P < 0.05). The improvement in 40-min all-out performance was associated with the change toward achieving peak torque earlier in the pedal stroke (r = 0.66, P < 0.01). Neither of the groups displayed alterations in VO2max or cycling economy. In conclusion, heavy strength training leads to improved cycling performance in elite cyclists as evidenced by a superior effect size of ES training vs E training on relative improvements in power output at 4 mmol L−1 [la−], peak power output during 30-s Wingate test, Wmax, and mean power output during 40-min all-out trial.
    Scandinavian Journal of Medicine and Science in Sports 06/2014; 25(1). DOI:10.1111/sms.12257 · 2.90 Impact Factor
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