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[This corrects the article DOI: 10.1371/journal.pone.0194057.].

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PURPOSE: Strength training improves distance running economy and performance. This finding is based predominantly on maximal and explosive strength programmes applied to locomotor muscles, particularly on the lower limbs. It is not certain whether a minimization of metabolic cost (Cmet) and an improvement in running performance is feasible with strength training of the postural and trunk muscles. METHODS: Using kinematic, neuromuscular and metabolic measurements of running at two different speeds before and after a 12-week Pilates training programme, we tested the hypothesis that core training might improve the running Cmet and performance of trained runners. Thirty-two individuals were randomly assigned to the control group (CG, n = 16) or the Pilates group (PG, n = 16). RESULTS: Confirming our hypothesis, a significant improvement (p<0.05) was observed for running performance in the PG (pre: 25.65±0.4 min; post: 23.23±0.4 min) compared to the CG (pre: 25.33±0.58 min; post: 24.61±0.52 min). Similarly, the PG (4.33±0.07 J.kg-1.m-1) had better responses than the CG (4.71±0.11 J.kg-1.m-1) during post-training for Cmet. These findings were accompanied by decreased electromyographic activity of the postural muscles at submaximal running intensities in the PG. CONCLUSIONS: Overall, these results provide a rationale for selecting strength training strategies that target adaptations on specific postural and locomotor muscles for trained distance runners.

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The purpose of this study was to determine cardiorespiratory responses in pregnant and nonpregnant women during the execution of resistance exercises for upper and lower body. Twenty healthy women (10 pregnant: 22-24 weeks, 25.20 ± 4.44 years, 69.80 ± 9.52 kg, 161.60 ± 5.21 cm and 10 nonpregnant: 25.20 ± 3.73 years, 62.36 ± 8.60 kg, 162.40 ± 3.97 cm) performed 5 experimental sessions. Session 1: familiarization with the equipments and the determination of 1 estimated maximum repetition. Sessions 2, 3, 4, and 5: determination of the cardiorespiratory responses during the execution of resistance exercise on the bilateral leg extension and pec-deck fly, with 1 and 3 sets of 15 repetitions, 50% of 1 estimated maximum repetition. Systolic, diastolic, and mean blood pressure (BP) responses were lower (p = 0.029, 0.018, 0.009, respectively) in the pregnant group. When the exercises were performed with a single set, heart rate showed increased values for bilateral leg extension (pregnant: 109.40 ± 10.75 b·min, nonpregnant: 108.51 ± 19.05 b·min) compared with pec-deck (pregnant: 101.59 ± 14.83 b·min, nonpregnant: 100.37 ± 12.36 b·min); however, when the exercises were performed with 3 sets, bilateral leg extension showed increased values for the heart rate (pregnant: 114.70 ± 13.58 b·min, nonpregnant: 121.29 ± 10.86 b·min), systolic (pregnant: 124.50 ± 17.32 mm Hg, nonpregnant: 136.00 ± 17.79 mm Hg), diastolic (pregnant: 68.10 ± 8.23 mm Hg, nonpregnant: 77.89 ± 15.25 mm Hg), and mean BP (pregnant: 86.90 ± 10.38 mm Hg, nonpregnant: 97.73 ± 12.64 mm Hg), ventilation (pregnant: 12.88 ± 4.05 L·min, nonpregnant: 15.02 ± 4.19 L·min), and oxygen consumption (pregnant: 0.41 ± 0.08 L·min, nonpregnant: 0.42 ± 0.09 L·min) compared with pec-deck fly exercise. We concluded that the pressure response was unaffected by pregnancy and showed to be safe during the performance of resistance exercises.

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