24 research outputs found
RELATIONSHIP BETWEEN VERTICAL JUMPS AND STARTING ACCELERATION IN SPRINT
The purpose of this study was to relate standardized vertical jumps with acceleration phase in sprint. Since vertical jumps employ typical kinetic chains and provide insight into basic movement strategies of the athlete, they may provide additional information about the nature of sprint acceleration phase
Selective effect of static stretching, concentric contractions, and a balance task on ankle force sense
Proper ankle motor control is critical for balance in the human body during functional activities
such as standing, walking, and running. Different exercise modalities are often performed
during the same training session where earlier activities may influence later ones.
The purpose of the current study was to determine the acute effects of different exercise
modalities on ankle force sense. Seventeen subjects performed four different intervention
protocols (static stretching, balance task, concentric contractions, and control) in random
order. Each session comprised measurements before and after the intervention protocol of
the force sense of the ankle plantar flexors (PF) and dorsal flexors (DF) at 10% and 30%
of maximal voluntary isometric contraction (MVC). Absolute errors (AE) were calculated
separately for each force level and muscle group. An overall PF error (PF-SUM = PF at 10%
MVC + PF at 30%MVC), DF error (DF-SUM = DF at 10%MVC + DF at 30%MVC) and ankle
error (PF-DF-SUM = PF-SUM + DF-SUM) were also calculated. The main effect of time
generally revealed that ankle force sense was significantly reduced after static stretching
(PF-DF-SUM: Pre: 6.11±2.17 Nm, Post: 8.03±3.28 Nm; p < 0.05), but no significant differences
were observed for the concentric contractions (PF-DF-SUM: Pre: 6.01±1.97 Nm,
Post: 6.50±2.28 Nm) and the balance task (PF-DF-SUM: Pre: 5.25±1.97 Nm, Post: 5.50
±1.26 Nm). The only significant interaction was observed for the PF-DF-SUM (F = 4.48, p =
0.008) due to greater error scores after stretching (+31.4%) compared to the concentric
(+8.2%), balance (+4.8%), and control (-3.5%) conditions. Based on these results, static
stretching should not be performed before activities that require a high ankle force sense
such as balance, coordination, and precision tasks.This work was supported by Javna
Agencija za Raziskovalno Dejavnost RS (SI) (P5-
0142 to DS)
Terminologija v poklicnem vsakdanu: stanje in potrebe
Terminologija v poklicnem vsakdanu: stanje in potreb
Neuromuscular Consequences of an Extreme Mountain Ultra-Marathon
We investigated the physiological consequences of one of the most extreme exercises realized by humans in race conditions: a 166-km mountain ultra-marathon (MUM) with 9500 m of positive and negative elevation change. For this purpose, (i) the fatigue induced by the MUM and (ii) the recovery processes over two weeks were assessed. Evaluation of neuromuscular function (NMF) and blood markers of muscle damage and inflammation were performed before and immediately following (nâ=â22), and 2, 5, 9 and 16 days after the MUM (nâ=â11) in experienced ultra-marathon runners. Large maximal voluntary contraction decreases occurred after MUM (â35% [95% CI: â28 to â42%] and â39% [95% CI: â32 to â46%] for KE and PF, respectively), with alteration of maximal voluntary activation, mainly for KE (â19% [95% CI: â7 to â32%]). Significant modifications in markers of muscle damage and inflammation were observed after the MUM as suggested by the large changes in creatine kinase (from 144±94 to 13,633±12,626 UI Lâ1), myoglobin (from 32±22 to 1,432±1,209 ”g Lâ1), and C-Reactive Protein (from <2.0 to 37.7±26.5 mg Lâ1). Moderate to large reductions in maximal compound muscle action potential amplitude, high-frequency doublet force, and low frequency fatigue (index of excitation-contraction coupling alteration) were also observed for both muscle groups. Sixteen days after MUM, NMF had returned to initial values, with most of the recovery process occurring within 9 days of the race. These findings suggest that the large alterations in NMF after an ultra-marathon race are multi-factorial, including failure of excitation-contraction coupling, which has never been described after prolonged running. It is also concluded that as early as two weeks after such an extreme running exercise, maximal force capacities have returned to baseline
Biomechanical characteristics of female sprinters during the acceleration phase and maximum speed phase
Etiology of Neuromuscular Fatigue After Repeated Sprints Depends on Exercise Modality
International audienc
Effect of fatigue on force production and force application technique during repeated sprints
International audienc
Effects of creeping exercise on upper limb strength
This study determined the influence of creeping exercise on the strength and endurance of the upper body. A total of 32 young football players were divided into an experimental (EXP) and a control group (CON). The EXP group included 17 boys (11.6±0.6years), while the CON group included 15 boys (10.5±1.1years). Upper body strength and endurance were measured by five motor performance tests: push-ups, pull-ups, pulling and pushing on a bench and a complex creeping exercise ("driving a wheelbarrow"). Strength training consisted of a creeping exercise (6 weeks, 2-3 sets, 2-3 times a week, 10-15 minutes). The EXP group improved their performance in push-ups and pull-ups by ~90% (p<0.05) and ~26% (p<0.05), respectively. No significant differences were observed when pulling or pushing on the bench, while the EXP group improved performance scores in "driving a wheelbarrow" by ~13% (p<0.01). For the CON group, motor tests either remained unchanged or decreased. A significantly lower number of repetitions (~20%; p<0.05) was achieved only for pull-ups. Creeping exercises improved the results in the selected upper body strength and motor performance tests. This improvement could be attributed to changes in the neural mechanisms of muscular force generation in the shoulder girdle and trunk
High-intensity sprint fatigue does not alter constant-submaximal velocity running mechanics and spring-mass behavior
International audienc
Neuromuscular Adaptations after an Altitude Training Camp in Elite Judo Athletes
The aim of this study was to investigate neuromuscular adaptations in elite judo athletes
after three weeks of power-oriented strength training at terrestrial altitude (2320 m). Nineteen men
were assigned to altitude training (AL) (22.1 ± 2.3 years) and sea level training (SL) (22.6 ± 4.1 years).
Neuromuscular assessment consisted of: (1) maximal isometric knee extensor (KE) torque, (2) KE
rate of torque development (RTD), (3) quadriceps activity and voluntary activation, (4) soleus Hreflex, (5) quadriceps single (TTW) and double twitch torque (TDB100) and contraction time (CTTW).
There were no significant differences between groups at baseline for any of the observed parameters.
Significant differences were found between groups in terms of change in RTD (p = 0.04). Cohenâs d
showed a positive significant effect (0.43) in the SL group and a negative significant effect (â0.58) in
the AL group. The difference between groups in changes in CTTW as a function of altitude was on
the edge of significance (p = 0.077). CTTW increased by 8.1 ± 9.0% in the AL group (p = 0.036) and
remained statistically unchanged in the SL group. Only the AL group showed a relationship between
changes in TTW and TDB100 and changes in RTD at posttest (p = 0.022 and p = 0.016, respectively).
Altitude induced differences in muscular adaptations likely due to greater peripheral fatigue.Spanish Ministry of Economy, Industry and Competitiveness under grant DEP2015-64350-P MINECO/FEDERSlovenian Research Agency (P5-0142)FPI pre-doctoral grant under grant BES -2016-07803