Helena Gapeyeva

Functional Performance, Maximal Strength, and Power Characteristics in Isometric and Dynamic Actions of Lower Extremities in Soccer Players

Requena, B, González-Badillo, JJ, Saez de Villareal, ES, Ereline, J, García, I, Gapeyeva, H, and Pääsuke, M. Functional performance, maximal strength, and power characteristics in isometric and dynamic actions lower extremities in soccer players. J Strength Cond Res 23(5): 1391-1401, 2009-The purposes of the present study were to determine muscle strength and power output characteristics in a group of professional soccer players and to identify their relationships with 2 functional performance tests (vertical jumping height and 15-m sprint time). Maximal strength and power indices attained against different loads in barbell back squat exercise, isometric maximal force of the knee extensor and plantar flexor muscles, isokinetic peak torque of the knee extensors muscles, vertical jumping height in squat and counter-movement jumps, and 15-m sprint time tests were assessed in 21 semiprofessional soccer players (age 20 ± 3.8 years). Correlation analyses were performed to examine the relationship between each of these measures. The main results of the present study were that (a) maximal power in concentric half-squat exercise was attained with a load of 60% of 1 repetition maximum, representing 112% of body weight; (b) the performance in the functional tests selected was significantly related with all the half-squat variables measured, especially with loads of 75-125% of body weight; and (c) low to nonsignificant correlations were found between functional tests performance and isometric and isokinetic muscle strength measures. It was concluded that in semiprofessional soccer players (a) isometric and isokinetic muscle strength assessed in an open kinetic chain were not movement-specific enough to predict performance during a more complex movement, such as jump or sprint and (b) concentric half-squat exercise was principally related with the functional tests selected when it was performed against external loading within the range of the load in case of which the maximal power output was attained.

Twitch contraction properties of plantar flexor muscles in pre- and post-pubertal boys and men.

Abstract This study compared electrically evoked twitch contraction characteristics of the plantar flexor muscles in pre-pubertal (11-year-old) and post-pubertal (16-year old) boys, and young (19- to 23-year-old) men. The posterior tibial nerve was stimulated by supramaximal square-wave pulses of 1 ms duration at rest and after brief (5 s) isometric maximal voluntary contraction (MVC) of the plantar flexor muscles, i.e. during post-activation potentiation. Men had higher MVC force than boys and post-pubertal boys higher than pre-pubertal boys. Pre-pubertal boys had lower peak twitch forces (Pt) at rest and when potentiated compared with post-pubertal boys and men, whereas no significant differences were found between post-pubertal boys and men. Pre-pubertal boys had higher ratios of Pt at rest and potentiated Pt to MVC force than post-pubertal boys and men. No age-related differences were obtained in post-activation potentiation, rest and potentiated twitch contraction and half-relaxation time, and MVC force relative to body mass. The main findings of the study were that puberty is characterized by increased muscle force-generating capacity with no change in twitch potentiation and time-course characteristics, and that twitch force-generating capacity develops in an adult-like pattern after puberty.

RELATIONSHIP BETWEEN POSTACTIVATION POTENTIATION OF KNEE EXTENSOR MUSCLES, SPRINTING AND VERTICAL JUMPING PERFORMANCE IN PROFESSIONAL SOCCER PLAYERS

Requena, B, de Villarreal, ESS, Gapeyeva, H, Ereline, J, García, I, and Pääsuke, M. Relationship between postactivation potentiation of knee extensor muscles, sprinting and vertical jumping performance in professional soccer players. J Strength Cond Res 25(2): 367-373, 2011-Little is known about the relationship between postactivation potentiation (PAP) in human muscles, assessed by enhancement of twitch torque after a conditioning maximal voluntary contraction (MVC), and performance in activities requiring power and speed. Moreover, no studies have assessed PAP in soccer players who train power and endurance simultaneously. The purpose of the present study was to examine the relationship between twitch PAP in knee extensor (KE) muscles, and sprinting and vertical jumping performance in soccer players. Fourteen professional male soccer players with mean (SD) age 20.0 (3.6) years, height 177.9 (6.9) cm and body mass 70.5 (5.7) kg) were tested for 15-m sprint time, vertical jump height in countermovement (CMJ) and squat (SJ) jumps. PAP in KE muscles was induced by a 10-s isometric MVC. Electrically evoked twitches of KE muscles were evoked before and after the conditioning MVC. Immediately after the conditioning MVC, twitch peak torque (PT) and maximal rates of torque development and relaxation were significantly potentiated. A significant negative correlation was found between 15-m sprint time and jump height in CMJ (r = −0.63) and SJ (r = −0.57). PAP of twitch PT correlated significantly positively with jump height in CMJ (r = 0.61) and SJ (r = 0.64), and negatively with 15-m sprint time (r = −0.59). In conclusion, twitch PAP in KE muscles was significantly correlated with performance in vertical jumping and sprinting in male professional soccer players, whereas the magnitude of PAP in soccer players was similar to that observed previously in power-trained athletes.

Twitch contractile properties of plantar flexor muscles in power and endurance trained athletes.

Abstract This study compared twitch contractile properties of plantar flexor muscles among three groups of 12 subjects each: endurance and power trained athletes and untrained subjects. The posterior tibial nerve was stimulated by supramaximal square wave pulses of 1-ms duration. Power trained athletes had higher twitch maximal force, maximal rates of force development and relaxation and also maximal voluntary contraction (MVC) force. The trained subjects had a smaller twitch maximal force: MVC force ratio and shorter twitch contraction and half-relaxation times than the untrained subjects with no significant differences between the two groups. Thus, the short time for evoked twitches in the athletes compared to the untrained subjects would seem unrelated to the type of training. It is concluded that power training induces a more evident increase of muscle force-generating capacity and speed of contraction and relaxation than endurance training.

The Impact of Different Diagnostic Criteria on the Prevalence of Sarcopenia in Healthy Elderly Participants and Geriatric Outpatients

Background: A consensus on the diagnostic criteria for sarcopenia, a common syndrome in the elderly, has not been reached yet. Prevalence rates vary between studies due to the use of different criteria encompassing different measures, correction factors and cutoff points. Objective: This study compared prevalence rates of sarcopenia using nine sets of diagnostic criteria applied in two different elderly populations. Methods: The study population encompassed 308 healthy elderly participants (152 males, 156 females; mean age 74 years) and 123 geriatric outpatients (54 males, 69 females; mean age 81 years). Diagnostic criteria included relative muscle mass, absolute muscle mass, muscle strength and physical performance. Results: Prevalence rates of sarcopenia varied between 0 and 15% in healthy elderly participants and between 2 and 34% in geriatric outpatients. Conclusion: This study clearly demonstrates the dependency of sarcopenia prevalence rates on the applied diagnostic criteria.

Relationship between leg bone mineral values and muscle strength in women with different physical activity

This study examines whether knee extensor muscle isometric, isokinetic, and isoinertial strength values in women with different physical activity and body composition patterns are related to leg bone mineral density (BMD) and bone mineral content (BMC) values. A total of 129 women aged 17–40 participated in this study. They were divided into four groups: strength-trained (n = 33), endurance-trained (n = 32), normal weight sedentary (n = 41), and overweight sedentary (n = 23) women. In addition, the subjects were grouped as physically active (n = 65) or sedentary (n = 64) women. BMD and BMC for both legs (LBMD and LBMC, respectively) and for the dominant leg alone (DLBMC), body fat percentage and lean body mass (LBM), maximal knee extension isometric (ISOM) and isokinetic (ISOK) strength at the angular velocity of 60 deg·s−1, and isoinertial leg explosive strengths (countermovement jump CMJ) were measured. In endurance-trained women, LBMD was dependent on body mass index (BMI) (33.7% of the variance, R2 × 100), and in the physically active group and the total group with LBM (14.6% and 15.6%, respectively). In the overweight group, LBMD was dependent on ISOK strength (21.7% of the variance, R2 × 100). In the sedentary and total groups, ISOM strength was more important (10.3% and 5.0%, respectively); in the strength-trained group, body weight influenced LBMC, accounting for 71.6% of the variance (R2 × 100). In the endurance-trained women, height influenced LMBC (37.9%, R2 × 100). In sedentary and overweight women, LBM accounted for 52.1% and 61.4% of the total variance in LBMC. In these groups, ISOM strength accounted for 15.3% and 25.9% of the variance in LBMC. In overweight women, ISOM and ISOK strength together influenced LBMC highly (64.8% of the variance, R2 × 100). In the sedentary group, the influence of LBM on LBMC was higher than in the active group (82.1% and 50.5% of the variance, respectively). In the total group, LBM influenced LBMC, accounting for 54.5% of the variance (R2 × 100). ISOM strength (22.7%) alone or in combination with ISOK strength (35.8%) and CMJ (41.7%) (R2 × 100) in LBMC in the sedentary group explained the variance. In the total group, ISOM strength alone (13.2%) or in combination with CMJ (17.1%) influenced LBMC (R2 × 100). Our results suggest that (1) muscle strength and anthropometrical parameters were associated with LBMD; (2) LBM and ISOM strength had a significant relationship with DLBMC and LBMC only in nonathletic women; and (3) strength measured with different regimens highly influenced LBMC compared with LBMD, especially in the sedentary groups.

Lower limb performance in older female patients with Parkinson’s disease

Aims: This study examined lower limb performance in older sedentary patients with Parkinson’s disease (PD). Methods: Fourteen female patients with mild to moderate PD and 12 age-matched controls were included in this study. The force preparation and production of the knee extensor muscles during maximal isometric contraction were measured by dynamometric chair. Two force plates were used to measure the chair rising performance. Results: PD patients had longer visual reaction time during performing maximal isometric contraction,and lower maximal isometric force (MF) and rate of force development of the knee extensor muscles compared with controls. However, MF relative to body weight (BW)did not differ significantly in PD patients and controls. A longer chair rising time and lower maximal rate of vertical ground reaction force (VGRF) development while rising from a chair were found in PD patients compared with controls. No significant differences in maximal VGRF, and the sum of maximal VGRF of the right and left legs relative to the BW while rising from a chair were observed between the groups. In PD patients, chair rising time correlated negatively with MF of the knee extensor muscles. PD subjects also showed a positive correlation between the BW-related maximal VGRF while rising from a chair and MF of the knee extensor muscles relative to BW. Conclusions: These data suggest that subjects with PD are more deficient in the regulation of force-time parameters, rather than simply in force production of the knee extensor muscles.

Associations between muscle strength, spirometric pulmonary function and mobility in healthy older adults

Pathological obstruction in lungs leads to severe decreases in muscle strength and mobility in patients suffering from chronic obstructive pulmonary disease. The purpose of this study was to investigate the interdependency between muscle strength, spirometric pulmonary functions and mobility outcomes in healthy older men and women, where skeletal muscle and pulmonary function decline without interference of overt disease. A total of 135 69- to 81-year-old participants were recruited into the cross-sectional study, which was performed as a part of European study MyoAge. Full, partial and no mediation models were constructed to assess the interdependency between muscle strength (handgrip strength, knee extension torque, lower extremity muscle power), spirometric pulmonary function (FVC, FEV1 and FEF50) and mobility (6-min walk and Timed Up and Go tests). The models were adjusted for age, sex, total fat mass, body height and site of enrolment. Partial mediation models, indicating both direct and pulmonary function mediated associations between muscle strength and mobility, fitted best to the data. Greater handgrip strength was significantly associated with higher FVC, FEV1 and FEF50 (p < 0.05). Greater muscle power was significantly associated with better performance in mobility tests. Results suggest that decline in mobility with aging may be caused by decreases in both muscle strength and power but also mediated through decreases in spirometric pulmonary function. Future longitudinal studies are warranted to better understand how loss of function and mass of the respiratory muscles will affect pulmonary function among older people and how these changes are linked to mobility decline.

Spinal curvature and trunk muscle tone in rhythmic gymnasts and untrained girls

The aim of this study was to compare spinal curvature and muscle tone characteristics in elite female rhythmic gymnasts (n = 32) and untrained controls (n = 48). Results showed that the angles of lumbar lordosis (LL) and thoracic kyphosis (TK) were lower (p < 0.001) in gymnasts in comparison with the control group. It was evident that the vertebral column of gymnasts had straightened in thoracic as well as in lumbar part of the spine. The trunk flexors in gymnasts were undertoned, the tone of rectus abdominis muscle was lower (p < 0.001) in gymnasts compared to that of the control group, while tone of erector spinae muscle (trunk extensor) was not differed from the control group. The tone of spinal muscles was higher (p < 0.001) than that of abdominal muscles in gymnasts, whereas the tone of these muscles did not differ significantly in controls. In the control group, the tone of trunk flexor and extensor muscles were in balance, whereas in gymnasts it was imbalanced. The indicator of tone imbalance of the trunk flexor and extensor muscles correlated negatively with the difference in body height in supine and standing positions (L) (r = −0.66, p < 0.001) for the group of gymnasts. In gymnast, TK and LL correlated negatively with Oswestry score (r = −0.68, p < 0.05 and r = −0.66, p < 0.05, respectively) and positively with L (r = 0.63, p < 0.05 and r = 0.60, p < 0.05 respectively). This indicates that the more rigid vertebral column, flattened in thoracal and lumbar part that appeared in gymnasts, associated with imbalance in muscle tone and low back pain (LBP). In 50% of measured gymnasts, LBP incidence

Back extensor muscle fatigability in chronic low back pain patients and controls: Relationship between electromyogram power spectrum changes and body mass index.

Back extensor muscle fatigability and its relationship to body mass index (BMI) was measured in 12 chronic nonspecific low back pain (CNLBP) patients (7 women and 5 men) and 12 healthy age-and gender-matched controls. Subjects performed Sørensen back isometric endurance test until exhaustion while EMG spectral mean power frequency (MPF) over the lumbar erector spinae muscle and endurance time were recorded. The CNLBP patients had significantly shorter endurance time than healthy controls. Spectral MPF significantly declined as time of isometric contraction progressed. Relative decrease of the MPF per minute (MPF slope) for left and right side, and pooled MPF slope was significantly higher in CNLBP patients compared with controls. In CNLBP patients the isometric endurance time correlated significantly negatively with BMI (r=-0.71). In controls BMI correlated significantly positively with MPF slopes of left (r=0.68) and right (r=0.57) side, and pooled MPF slope (r=0.62).