This study investigated protein kinase activation and gene expression of angiogenic factors in response to low-load resistance exercise with or without blood flow restriction (BFR). In a repeated measures cross-over design, six males performed four sets of bilateral knee extension exercise at 20% 1RM (reps per set = 30:15:15:continued to fatigue) with BFR (110 mmHg) and without (CON). Muscle biopsies were obtained from the vastus lateralis before, 2 and 4 h post-exercise. mRNA expression was determined using real-time RT-PCR. Protein phosphorylation/expression was determined using Western blot. p38MAPK phosphorylation was greater (p = 0.05) at 2 h following BFR (1.3 ± 0.8) compared to CON (0.4 ± 0.3). AMPK phosphorylation remained unchanged. PGC-1α mRNA expression increased at 2 h (5.9 ± 1.3 vs. 2.1 ± 0.8; p = 0.03) and 4 h (3.2 ± 0.8 vs. 1.5 ± 0.4; p = 0.03) following BFR exercise with no change in CON. PGC-1α protein expression did not change following either exercise. BFR exercise enhanced mRNA expression of vascular endothelial growth factor (VEGF) at 2 h (5.2 ± 2.8 vs 1.7 ± 1.1; p = .02) and 4 h (6.8 ± 4.9 vs. 2.5 ± 2.7; p = .01) compared to CON. mRNA expression of VEGF-R2 and hypoxia-inducible factor 1α increased following BFR exercise but only eNOS were enhanced relative to CON. Matrix metalloproteinase-9 mRNA expression was not altered in response to either exercise. Acute low-load resistance exercise with BFR provides a targeted angiogenic response potentially mediated through enhanced ischaemic and shear stress stimuli.

BackgroundEndurance capacity is one of the main performance determinants in handcycling. There are two exercise test procedures primarily applied to determine endurance capacity, to verify training adaptations and predict race performance. This study aims to evaluate the agreement of these applied concepts in handcycling.MethodsIn a repeated measures cross-over design, 11 highly trained male spinal cord injured (Th12 to L1) handcyclists (age: 40 ± 9 years, height: 183 ± 8 cm, body mass: 73.2 ± 8.5 kg) performed a graded exercise test (GXT) and a lactate minimum test (LMT) to determine lactate threshold at 4 mmol L–1 (LT4 mmol L−1) and lactate minimum (LM), respectively. The agreement of both lactate thresholds concepts for constant load performance prediction (change of ≤ 1 mmol L–1 during the last 20 min) was evaluated within constant load tests (CLT; 30 min) at a power output (PO) corresponding to LT4 mmol L–1 and LM. Oxygen uptake (V.⁢O2), respiratory exchange ratio (RER), heart rate (HR) and blood lactate (La) were measured during all tests.ResultsPower output at the corresponding thresholds (LT4 mmol L−1: 149 ± 34 W vs. LM: 137 ± 18 W) revealed no significant difference (p = 0.06). During the CLT at LT4 mmol⋅L−1 and LM, V.⁢O2, and RPE were not significantly different. However, LA, RER, and HR were significantly higher (p ≤ 0.02) during CLT at LT4 mmol L−1. Bland–Altman plots indicate a wide range of dispersion for all parameters between both lactate threshold concepts. Evaluations of LT4 mmol L−1 and LM did not meet the criteria for constant load performance within the CLT for 33 and 17% of the athletes, respectively.DiscussionBoth exercise tests and the corresponding lactate threshold concept revealed appropriate estimates to predict a steady state performance for the majority of participants. However, as PO determination at LT4 mmol L−1 and LM exceeds the criteria for constant load performance (increase of ≥ 1 mmol L–1) for 33 and 17% respectively the current results indicate the common criteria for constant load performance (change of ± 1 mmol L–1) might not be sufficiently precise for elite athletes in handcycling. Consequently, exercise test results of elite athletes should be analyzed individually and verified by means of several CLT.

Winter weather conditions restrict regular sport-specific endurance training in inline speed skating. As a result, this study was designed to compare the effects of cycling and running training programs on inline speed skaters' endurance performance. Sixteen (8 men, 8 women) high-level athletes (mean ± SD 24 ± 8 years) were randomly assigned to 1 of 2 groups (running and cycling). Both groups trained twice a week for 8 weeks, one group on a treadmill and the other on a cycle ergometer. Training intensity and duration was individually calculated (maximal fat oxidation: ∼52% of V[Combining Dot Above]O2peak: 500 kcal per session). Before and after the training intervention, all athletes performed an incremental specific (inline speed skating) and 1 nonspecific (cycling or running) step test according to the group affiliation. In addition to blood lactate concentration, oxygen uptake (V[Combining Dot Above]O2), ventilatory equivalent (VE/V[Combining Dot Above]O2), respiratory exchange ratio (RER), and heart rate were measured. The specific posttest revealed significantly increased absolute V[Combining Dot Above]O2peak values (2.9 ± 0.4, 3.4 ± 0.7, p = 0.01) and submaximal V[Combining Dot Above]O2 values (p ≤ 0.01). VE/V[Combining Dot Above]O2 and RER significantly decreased at maximal (46.6 ± 6.6, 38.5 ± 3.4, p = 0.005; 1.1 ± 0.03, 1.0 ± 0.04, p = 0.001) and submaximal intensities (p ≤ 0.04). None of the analysis revealed a significant group effect (p ≥ 0.15). The results indicate that both cycling vs. running exercise at ∼52% of V[Combining Dot Above]O2peak had a positive effect on the athletes' endurance performance. The increased submaximal V[Combining Dot Above]O2 values indicate a reduction in athletes' inline speed skating technique. Therefore, athletes would benefit from a focus on technique training in the subsequent period.