A NOVEL METHOD FOR INITIAL CONTACT DETECTION IN TREADMILL RUNNING USING SIDE RAIL REFLECTIVE MARKER

Treadmill running analysis is often preferred to overground running due to the small observation volume. Splitting the cyclic running motion into single cycles requires the robust detection of common features identifying the initial contact (IC). Kinematic features such as HEEL marker velocity zero-crossing (ZC) in vertical or anteroposterior direction are proposed in literature. In this study (n = 14 male, 3.5 m/s, 3 right steps, 8 VICON MX cameras, 250 fps) a novel treadmill mounted marker (TREA) is compared to these two features. TREA vertical velocity ZC appears (6.8 ± 12.8) ms after HEEL anteroposterior ZC and can therefore be used as an easy-to-use feature for IC detection in treadmill running. HEEL vertical velocity ZC is to be doubted as it appears (59.0 ± 19.7) ms later than TREA vertical velocity ZC

Influence of specific collagen peptides and 12-week concurrent training on recovery-related biomechanical characteristics following exercise-induced muscle damage—A randomized controlled trial

IntroductionIt has been shown that short-term ingestion of collagen peptides improves markers related to muscular recovery following exercise-induced muscle damage. The objective of the present study was to investigate whether and to what extent a longer-term specific collagen peptide (SCP) supplementation combined with a training intervention influences recovery markers following eccentric exercise-induced muscle damage.MethodsFifty-five predominantly sedentary male participants were assigned to consume either 15 g SCP or placebo (PLA) and engage in a concurrent training (CT) intervention (30 min each of resistance and endurance training, 3x/week) for 12 weeks. Before (T1) and after the intervention (T2), eccentric muscle damage was induced by 150 drop jumps. Measurements of maximum voluntary contraction (MVC), rate of force development (RFD), peak RFD, countermovement jump height (CMJ), and muscle soreness (MS) were determined pre-exercise, immediately after exercise, and 24 and 48 h post-exercise. In addition, body composition, including fat mass (FM), fat-free mass (FFM), body cell mass (BCM) and extracellular mass (ECM) were determined at rest both before and after the 12-week intervention period.ResultsThree-way mixed ANOVA showed significant interaction effects in favor of the SCP group. MVC (p = 0.02, ηp2 = 0.11), RFD (p < 0.01, ηp2 = 0.18), peak RFD (p < 0.01, ηp2 = 0.15), and CMJ height (p = 0.046, ηp2 = 0.06) recovered significantly faster in the SCP group. No effects were found for muscle soreness (p = 0.66) and body composition (FM: p = 0.41, FFM: p = 0.56, BCM: p = 0.79, ECM: p = 0.58).ConclusionIn summary, the results show that combining specific collagen peptide supplementation (SCP) and concurrent training (CT) over a 12-week period significantly improved markers reflecting recovery, specifically in maximal, explosive, and reactive strength. It is hypothesized that prolonged intake of collagen peptides may support muscular adaptations by facilitating remodeling of the extracellular matrix. This, in turn, could enhance the generation of explosive force.Clinical trial registrationClinicalTrials.gov, identifier ID: NCT05220371

Anterior subject positioning affects the maximal exerted isometric plantar flexion moment.

We examined the effect of increased anterior subject positioning toward the dynamometer's footplate during maximal voluntary isometric contractions (MVCs) on the joint moment, rotation and rate of torque development (RTD). Fourteen subjects, with their hip flexed (110°) and knee fully extended (180°), underwent ramp maximal and rapid voluntary isometric plantar flexion contractions at 4 different positions (0, 3, 6 and 8 cm; randomized). At position "0 cm", the foot was in full contact with the footplate; at the additional positions, the chair was moved forward. Body kinematics (VICON) and kinetics (HUMAC Norm, PEDAR) were captured synchronously during MVCs and RTDs. The results showed that the maximal exerted joint moment was significantly (p32% from the 0-cm to 8-cm position (126 and 172 Nm, respectively); however, at the "6 cm" and "8 cm" positions, no significant difference was found. The joint rotation was significantly (p50% (from 15.5 to 7.1°; 0-8 cm). The maxRTD was only significantly higher at "6 cm" compared with the "0 cm" position. The time to reach maxRTD showed shorter tendencies for the "8 cm" position than for all other positions. The results indicate an underestimation of the plantar flexor maximal force potential with the current measuring technique. This could be critical in pre-post study designs where a 2-cm alteration in the chair position can induce an error of ~9% in the joint moment. The joint rotation could be reduced but not completely eliminated. For position standardization purposes, a pressure >220 kPa under the subject's foot is needed to achieve the maximal joint moment. We discussed the possible origins (fascicle length, neural drive) of the increased joint moment