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1.
Front Sports Act Living ; 6: 1407601, 2024.
Article in English | MEDLINE | ID: mdl-38783868

ABSTRACT

Given the complex nature of the handball as a game, players are required to possess a distinct set of physical and physiological attributes to attain peak performance. With the countermovement vertical jump (CVJ) being widely implemented as a non-invasive and time-efficient testing modality in sports settings, the purpose of the present study was twofold: (a) to establish a CVJ profile of professional female handball players and (b) to examine differences in force-time metrics between starters and non-starters. Forty-two professional female handball players (e.g., SuperLeague) volunteered to participate in this study. Each athlete performed three maximum-effort CVJs with no arm swing while standing on a uni-axial force plate system sampling at 1,000 Hz. Independent t-tests were used to examine differences in each variable between starters and non-starters. The results revealed that starters attained superior performance within the eccentric phase of the CVJ when compared to non-starters, particularly in terms of eccentric peak velocity (-0.957 ± 0.242 vs. -0.794 ± 0.177 m·s-1), eccentric mean power (320.0 ± 77.7 vs. 267.1 ± 75.2 W), and eccentric peak power (929.0 ± 388.1 vs. 684.4 ± 214.2 W). While not reaching the level of statistical significance, moderate-to-large effect sizes were observed for concentric impulse, peak velocity, and mean and peak force and power, all in favor of players included in the starting lineup (g = 0.439-0.655). Overall, these findings suggest that at the top-tier level of handball competition, the ability to secure a spot in a starting lineup may be possibly influenced by the athlete's eccentric performance capabilities. Thus, the development of lower-body eccentric strength and power may positively impact on-court athlete performance and ultimately help the team secure the desired game outcome.

2.
J Strength Cond Res ; 37(11): e609-e612, 2023 Nov 01.
Article in English | MEDLINE | ID: mdl-37883409

ABSTRACT

ABSTRACT: Cabarkapa, D, Cabarkapa, DV, Philipp, NM, Knezevic, OM, Mirkov, DM, and Fry, AC. Pre-post practice changes in countermovement vertical jump force-time metrics in professional male basketball players. J Strength Cond Res 37(11): e609-e612, 2023-Despite the countermovement vertical jump (CVJ) being one of the most popular noninvasive and time-efficient methods for monitoring neuromuscular status, there is a lack of scientific literature focused on examining fatigue-induced alterations in performance in elite athletes. Thus, the purpose of this study was to examine changes in force-time metrics pre-post practice in professional male basketball players. Seventeen athletes competing in first-tier and second-tier national basketball leagues in Europe participated in this study. While standing on a uniaxial force plate sampling at 1,000 Hz, each athlete completed 3 CVJs pre-practice and post-practice. The practice consisted of individual and team shooting drills, position-specific player development drills, 5-on-0 offensive actions, and 5-on-5 play, including full-court transition (∼2 hours). The findings reveal that pre-post practice changes in force-time metrics seem to be phase specific. Despite a trivial increase in eccentric mean force (920.4 ± 100.2, 929.4 ± 100.0 N), most changes were observed within the concentric phase of the CVJ. The concentric phase duration increased pre-post practice (0.233 ± 0.027, 0.242 ± 0.033 seconds), whereas concentric impulse (262.9 ± 18.8, 258.6 ± 21.6 N·s), peak velocity (2.93 ± 0.22, 2.86 ± 0.22 m·s-1), mean force (2052.4 ± 179.2, 2002.7 ± 188.2 N), mean power (3,165.5 ± 269.5, 3,030.9 ± 326.8 W), and peak power (5,523.4 ± 607.3, 5,246.6 ± 663.7 W) experienced a significant decrease. Moreover, alongside longer contraction time (0.663 ± 0.065, 0.686 ± 0.074 seconds), lower vertical jump height (41.0 ± 6.8, 38.9 ± 6.6 cm) and reactive strength index-modified (0.634 ± 0.113, 0.579 ± 0.111 m·s-1) values were observed post-practice. Overall, these findings may allow practitioners to detect fatigue-induced changes in CVJ force-time metrics in professional male basketball players that can ultimately improve the acute and longitudinal training-adaptation monitoring process.


Subject(s)
Athletic Performance , Basketball , Humans , Male , Muscle Strength , Athletes , Europe
3.
Life (Basel) ; 13(1)2023 Jan 09.
Article in English | MEDLINE | ID: mdl-36676138

ABSTRACT

The purpose of the present study was (i) to explore the reliability of the most commonly used countermovement jump (CMJ) metrics, and (ii) to reduce a large pool of metrics with acceptable levels of reliability via principal component analysis to the significant factors capable of providing distinctive aspects of CMJ performance. Seventy-nine physically active participants (thirty-seven females and forty-two males) performed three maximal CMJs while standing on a force platform. Each participant visited the laboratory on two occasions, separated by 24-48 h. The most reliable variables were performance variables (CV = 4.2-11.1%), followed by kinetic variables (CV = 1.6-93.4%), and finally kinematic variables (CV = 1.9-37.4%). From the 45 CMJ computed metrics, only 24 demonstrated acceptable levels of reliability (CV ≤ 10%). These variables were included in the principal component analysis and loaded a total of four factors, explaining 91% of the CMJ variance: performance component (variables responsible for overall jump performance), eccentric component (variables related to the breaking phase), concentric component (variables related to the upward phase), and jump strategy component (variables influencing the jumping style). Overall, the findings revealed important implications for sports scientists and practitioners regarding the CMJ-derived metrics that should be considered to gain a comprehensive insight into the biomechanical parameters related to CMJ performance.

4.
Front Physiol ; 13: 874632, 2022.
Article in English | MEDLINE | ID: mdl-35784865

ABSTRACT

The main objective of present study was to evaluate inter-rater reliability and concurrent validity of Side Hop Test stopwatch vs. force plates timing, and to determine the number of sessions and trials required to minimize the effects of learning on Side Hop Test total time and limb symmetry index. Fifteen healthy male physical education students (mean ± SD: age, 23 ± 3 years; height, 181 ± 9 cm; and weight 72 ± 6 kg) participated. Side Hop Test total time (stopwatch and force plates) of left and right leg, and limb symmetry index (force plates) were obtained over seven sessions conducted 5-7 days apart. Time recordings of two raters were similar (t = -0.56, p > 0.05) with high reliability (all ICC >0.99 and CV% <0.1) and no systematic bias when compared to force plate data (p > 0.05; for rater 1 and 2, respectively). Total time improved across the Sessions (F = 25.87, p < 0.01, ω 2 = 0.18) and Trials (F = 68.15, p < 0.01, ω 2 = 0.10), with no significant interaction between factors. No between-leg differences were detected (F = 0.52, p > 0.05, ω 2 = 0.001). Limb symmetry index ranged from 0.999 to 1.055 across all sessions and trials (all p > 0.05 and ω 2 < 0.00). Due to low coefficient of correlation, high interclass correlation coefficient, and the lack in heteroscedasticity, stopwatch measurements are valid to measure total time in the Side Hop Test. Moreover, stopwatch measurements could be reliably used to measure total time in the Side Hop Test, while the test could be administrated with only one experienced rater. Unlike total times, findings on limb symmetry index suggest it could be reliably assessed after seven familiarization sessions.

5.
Front Physiol ; 13: 849275, 2022.
Article in English | MEDLINE | ID: mdl-35812338

ABSTRACT

Over the past decade, force-velocity (F-v) profiling has emerged as a promising tool for assessing neuromuscular capacity to design individually tailored interventions in diverse populations. To date, a limited number of studies have addressed the optimization of the linear method for measuring F-v profiles of single-joint isokinetic movements. We aimed to simplify the measurement of knee extension (KE) and knee flexion (KF) isokinetic tasks by evaluating the most appropriate combination of two velocities (i.e., the 2-point method). Twenty-two healthy participants (11 males and 11 females) were included in the study. Isokinetic peak torque was measured at nine angular velocities (30-60-90-120-150-180-210-240-300°/s) and under isometric conditions (at 150° and 120° of KF for KE, and KF, respectively). Maximal theoretical force (F0), maximal theoretical velocity (v0), slope of the relationship (Sfv) and maximal theoretical power (Pmax) were derived from the linear F-v profiles of KE and KF and compared between the 9-point method and all possible combinations (36 in total) of the 2-point methods. The F-v profiles obtained from nine points were linear for KE (R2 = 0.95; 95% CI = 0.94-0.96) and KF (R2 = 0.93; 95% CI = 0.90-0.95), with F0 underestimating isometric force. Further analyses revealed great to excellent validity (range: ICCs = 0.89-0.99; CV = 2.54%-4.34%) and trivial systematic error (range: ES = -0.11-0.24) of the KE 2-point method when force from distant velocities (30°/s, 60°/s or 90°/s combined with 210°/s, 240°/s or 300°/s) was used. Similarly, great to excellent validity and trivial systematic error of the KF 2-point method for F0 and Pmax (range: ICC = 0.90-0.96; CV = 2.94%-6.38%; ES = -0.07-0.14) were observed when using the previously described combinations of velocities. These results suggest that practitioners should consider using more distant velocities when performing simplified isokinetic 2-point single-joint F-v profiling. Furthermore, the F-v profile has the potential to differentiate between the mechanical properties of knee extensors and flexors and could therefore serve as a potential descriptor of performance.

6.
Sports Biomech ; : 1-15, 2022 Mar 15.
Article in English | MEDLINE | ID: mdl-35287552

ABSTRACT

The present study aimed to explore the possibility of comprehensively assessing whole-body muscle strength by testing as few muscle groups as possible, using a single testing method (isometric or isokinetic dynamometry) and a single variable (maximal force or rate of force development). Knee, hip, shoulder and elbow extensors and flexors were evaluated in males with high (n = 26) and low strength levels (n = 32). The principal component analysis revealed three factors that explained 62.5% of the total variance, while the main factors were loaded by the different testing methods and strength variables for the muscles acting on the knee (first component), hip (second component) and arm joints (third component). These results were confirmed by a three-way ANOVA which revealed a significant factor of group (P < 0.001) and the interaction test type × group (P = 0.002), but not of test type (P = 0.644), muscle group (P = 0.999), or their interactions (P > 0.205). The correlations of strength outcomes across the muscles ranged from trivial to very large (r range = -0.17, 0.84), being generally higher for the antagonistic muscles. Overall, a comprehensive assessment of whole-body muscle strength can be obtained using isometric dynamometry and maximal force, but it should consider at least one muscle group from the antagonistic pair.

7.
Sports Biomech ; 21(9): 1136-1145, 2022 Oct.
Article in English | MEDLINE | ID: mdl-32223526

ABSTRACT

This study aimed to compare the magnitude of the force-velocity (F-V) relationship parameters (maximum force [F0], maximum velocity [V0], F-V slope, and maximum power [Pmax]) between the squat jumps (SJ) performed from different knee angles. The F-V relationships of 12 men were assessed in 3 sessions during the SJ performed from a knee angle of 80° (SJ80), 90° (SJ90) and 100° (SJ100). The SJ100 provided likely to very likely higher values of F0 and Pmax compared to SJ80 (86% and 98%, respectively) and SJ90 (73% and 94%, respectively), while unclear and trivial differences were observed for the remaining comparisons. The magnitude of the correlations between the 3 SJ types was very large to nearly perfect for Pmax (r range = 0.864 to 0.940), moderate to very large for F0 (r range = 0.438 to 0.778), and small to large for V0 (r range = 0.361 to 0.642) and the F-V slope (r range = 0.178 to 0.645). These results suggest that the F-V relationship assessed during the SJ exercise is affected by the initial knee angle with the increase of the knee angle from 80° to 100° being associated with higher values of F0 and Pmax, while V0 remains unchanged.


Subject(s)
Knee , Lower Extremity , Biomechanical Phenomena , Humans , Knee Joint , Male , Posture
8.
J Hum Kinet ; 80: 49-59, 2021 Oct.
Article in English | MEDLINE | ID: mdl-34868416

ABSTRACT

The assessment of the force-velocity (F-V) profile in athletes may have important applications for training prescription, injury management, and fatigue monitoring. This study aimed to assess whether a novel single kayak stroke test (SKST) is able to provide the F-V relationship variables (maximum force, maximum velocity and maximum power) of competitive kayakers with acceptable reliability and external validity. Six female (age: 20.3 ± 3.7 years) and eight male (age: 20.8 ± 2.4 years) elite kayakers performed the SKST, bench press, bench pull, and short Wingate kayak test. The individual F-V relationships were highly linear [median r (range): left stroke = 0.986 (0.897 - 0.998); right stroke = 0.987 (0.971 - 0.999)]. The reliability of the F-V relationship parameters obtained during the SKST was high (within-session: CV ≤ 4.48% and ICC ≥ 0.93; between-session: CV ≤ 8.06% and ICC ≥ 0.65). The validity of the F-V relationship parameters obtained during the SKST was generally very high for maximum power (r range = 0.825 - 0.975), high for maximum force during both the bench press and the bench pull (r range = 0.751 - 0.831), and high or moderate for maximal velocity during the bench pull (r = 0.770 - 0.829) and the bench press (r = 0.355 - 0.471), respectively. The SKST can be considered a feasible procedure for testing the maximal upper-body muscle mechanical capacities of kayakers.

9.
Front Physiol ; 12: 709263, 2021.
Article in English | MEDLINE | ID: mdl-34899366

ABSTRACT

The aim of this study was to investigate the resistance-specific gains in muscle power and strength (1RM) following the training of maximum bench-press throws (BPT) against constant, inertial, and combined resistance. Forty-eight male participants (age 20.5 ± 2.0 years) were randomly assigned to the constant, inertial, combined resistance, or control group. Participants underwent 8 weeks of training of BPT against the loads that corresponded to the different effects of mass of 40 kg (∼50% of 1RM). The gains in average and maximum power, and 1RM were significant in all experimental groups (P < 0.01), but not in the control group (P > 0.1). Relative gains in the average (26.3 ± 9.8%) and maximum power (25.2 ± 9.8%) were larger than that in the 1RM (mean 7.2 ± 6.9%; both P < 0.001). The gains in the average (F 4, 66 = 6.0; P < 0.01) and maximum power (F 4, 66 = 4.7; P < 0.01) were higher when tested against the training-specific resistance than when tested against the remaining two resistance types. Differences in 1RM among experimental groups were not significant (P = 0.092). The most important and rather novel finding of the study is that the training against the weight and inertial resistance, and their combination results in resistance-specific gains in muscle power, although the overall gains muscle strength and power remain comparable across the training protocols.

10.
J Sports Sci Med ; 20(2): 357-364, 2021 06.
Article in English | MEDLINE | ID: mdl-34211329

ABSTRACT

This study aimed to assess the within- and between-session reliability of the KiSprint system for determining force-velocity-power (FVP) profiling during sprint running. Thirty (23 males, 7 females; 18.7 ± 2.6 years;) young high-level sprinters performed maximal effort sprints in two sessions separated by one week. Split times (5, 10, 20 and 30 m), which were recorded with a laser distance meter (a component of the KiSprint system), were used to determine the horizontal FVP profile using the Samozino's field-based method. This method assesses the FVP relationships through estimates of the step-averaged ground reaction forces in sagittal plane during sprint acceleration using only anthropometric and spatiotemporal (split times) data. We also calculated the maximal theoretical power, force and velocity capabilities and the slope of the FV relationship, the maximal ratio of horizontal-to-resultant force (RF), and the decrease in the RF (DRF). Overall, the results showed moderate or good to excellent within- and between-session reliability for all variables (ICC > 0.75; CV < 10 %), with the exception of FV slope and DRF that showed low relative reliability (ICC = 0.47-0.48 within session, 0.31-0.33 between-session) and unacceptable between-session absolute reliability values (CV = 10.9-11.1 %). Future studies are needed to optimize the protocol in order to maximize the reliability of the FVP variables, especially when practitioners are interested in the FV slope and DRF. In summary, our results question the utility of the sprint-based FVP profiling for individualized training prescription, since the reliability of the FV slope and D RF variables is highly questionable.


Subject(s)
Accelerometry/methods , Athletic Performance/physiology , Running/physiology , Acceleration , Adolescent , Biomechanical Phenomena , Female , Humans , Male , Reproducibility of Results , Time and Motion Studies , Young Adult
11.
Int J Sports Physiol Perform ; 16(2): 208-215, 2021 02 01.
Article in English | MEDLINE | ID: mdl-32942255

ABSTRACT

PURPOSE: To test whether the force-velocity (F-V) relationship obtained during a specific single-stroke kayak test (SSKT) and during nonspecific traditional resistance-training exercises (bench press and prone bench pull) could discriminate between 200-m specialists and longer-distance (500- and 1000-m) specialists in canoe sprint. METHODS: A total of 21 experienced male kayakers (seven 200-m specialists and 14 longer-distance specialists) participated in this study. After a familiarization session, kayakers came to the laboratory on 2 occasions separated by 48 to 96 hours. In a randomized order, kayakers performed the SSKT in one session and the bench press and bench pull tests in another session. Force and velocity outputs were recorded against 5 loads in each exercise to determine the F-V relationship and related parameters (maximum force, maximum velocity, F-V slope, and maximum power). RESULTS: The individual F-V relationships were highly linear for the SSKT (r = .990 [.908, .998]), bench press (r = .993 [.974, .999]), and prone bench pull (r = .998 [.992, 1.000]). The F-V relationship parameters (maximum force, maximum velocity, and maximum power) were significantly higher for 200-m specialists compared with longer-distance specialists (all Ps ≤ .047) with large effect sizes (≥0.94) revealing important practical differences. However, no significant differences were observed between 200-m specialists and longer-distance specialists in the F-V slope (P ≥ .477). CONCLUSIONS: The F-V relationship assessed during both specific (SSKT) and nonspecific upper-body tasks (bench press and bench pull) may distinguish between kayakers specialized in different distances.


Subject(s)
Exercise Test , Resistance Training , Water Sports , Athletes , Humans , Male , Muscle Strength
12.
Sports Biomech ; 20(8): 925-937, 2021 Dec.
Article in English | MEDLINE | ID: mdl-31232220

ABSTRACT

This study aimed to explore the effect of the knee angle and loading condition on the magnitude and reliability of squat jump (SJ) performance variables. Thirteen male sport sciences students performed in a random order 4 SJ types (knee angle of 80º [SJ80], 90º [SJ90], 100º [SJ100], and self-preferred [SJpref]) against 3 external loads. The push-off distance (HpO), jump height (Hmax), maximum force (Fmax) and maximum power (Pmax) were obtained from force platform recordings. The HpO during the SJpref (43.4 ± 6.4 cm) was always between SJ90 (44.3 ± 4.8 cm) and SJ100 (40.5 ± 4.2 cm). The magnitudes of Hmax, Fmax and Pmax were comparable or higher during the SJpref. The increase of the knee angle was associated with larger values of Fmax and Pmax, but no significant differences were observed for Hmax. An acceptable reliability was observed for HpO (coefficient of variation [CV]≤5.09% and intraclass correlation coefficient [ICC]≥0.78), Hmax (CV≤6.06% and ICC≥0.84), Fmax (CV≤3.25% and ICC≥0.96) and Pmax (CV≤2.93% and ICC≥0.96). Reliability did not systematically differ between the 4 SJ types. In conclusion, the higher magnitudes and comparable reliability of the performance variables obtained during the SJpref support its use for testing lower-body ballistic performance against different loads.


Subject(s)
Posture , Sports , Biomechanical Phenomena , Humans , Knee Joint , Male , Reproducibility of Results
13.
Article in English | MEDLINE | ID: mdl-33227905

ABSTRACT

BACKGROUND: Isokinetic testing has been routinely used to assess the capacities of individual muscle groups. In this study we aimed to evaluate the sensitivity of the force-point (F-v) relationship assessed through the two-point method to discriminate between antagonist muscle groups and males with different physical activity levels. METHODS: The concentric force output of the knee, hip, elbow, and shoulder flexors and extensors of 27 active and 13 non-active men was recorded at 60 and 180°/s to determine the F-v relationship parameters (maximum force [F0], maximum velocity [v0], and maximum power [Pmax]). RESULTS: F0 and Pmax were higher for knee extensors (effect size [ES] = 1.97 and 0.57, respectively), hip extensors (ES = 2.52 and 0.77, respectively), and shoulder flexors (ES = 1.67 and 0.83, respectively) compared to their antagonist muscles, while v0 was higher for knee flexors compared to knee extensors (ES = 0.59). Active males revealed higher F0 for knee extensors (ES = 0.72) and knee flexors (ES = 0.83) and higher Pmax for knee flexors (ES = 0.70), elbow extensors (ES = 0.83) and shoulder extensors (ES = 0.36). CONCLUSIONS: The sensitivity of the two-point method for testing the maximal mechanical capacities was high for the knee, moderate for the hip and shoulder, and low for the elbow joint.


Subject(s)
Biophysical Phenomena , Exercise , Joints , Muscle, Skeletal , Elbow , Exercise/physiology , Humans , Joints/physiology , Knee , Knee Joint , Male , Muscle, Skeletal/metabolism
14.
Article in English | MEDLINE | ID: mdl-32899837

ABSTRACT

(1) Background: Within the current study we aimed at exploring gender-related differences and the relationship between sprint start block kinematics and kinetics and sprint acceleration force-velocity (F-v) relationship parameters (maximal force [F0], maximal velocity [v0], maximal power [Pmax] and slope) in top national-level sprinters. (2) Methods: Twenty-eight sprinters (6 females) performed 10 maximal 30-m sprints. Start block and acceleration kinematics and kinetics were collected with an instrumented sprint start block and a laser distance sensor (KiSprint system). Displacement-time data were used to determine the F-v relationship through Samozino's method. (3) Results: Start block rear foot maximal force (effect size [ES] = 1.08), rate of force development (ES = 0.90-1.33), F0 (ES = 1.38), v0 (ES = 1.83) and Pmax (ES = 1.95) were higher in males than in females (p ≤ 0.05). There were no differences in the slope, and ratio of horizontal-to-resultant force. F0, v0, and Pmax generally presented higher correlations with the start block kinetics (median r [range] = 0.49 [0.28, 0.78]) than with the kinematics (median r [range] = -0.27 [-0.52, 0.28]). (4) Conclusions: We confirmed that sprint block phase and sprint acceleration mechanics should be mutually assessed when analyzing sprinting performance. KiSprint system could provide more accurate information regarding mechanical pattern and technique during sprint initiation and acceleration, and potentially help create a more personalized and effective training program.


Subject(s)
Athletic Performance , Running , Acceleration , Biomechanical Phenomena , Female , Humans , Male , Sex Factors
15.
Eur J Sport Sci ; 20(5): 614-623, 2020 Jun.
Article in English | MEDLINE | ID: mdl-31314671

ABSTRACT

This study aimed to compare the reliability and magnitude of the force-velocity (F-V) relationship parameters between the squat jumps performed from the 90° (SJ90) and self-preferred knee angle (SJpref). A secondary aim was to explore the effect of the analysis procedure (force platform [FP] and Samozino's [SAM] method) and the number of loads tested (three- and two-point methods) on the F-V relationships. Twelve men were tested in two sessions during the SJ90 and SJpref. Two identical blocks of jumps were performed in each session against three external loads. The F-V relationship parameters (maximum force, maximum velocity, F-V slope and maximum power) were determined at each block through the FP and SAM procedures using the data collected under three (three-point method) or only the two most distant loads (two-point method). The average coefficient of variation (CV) of the four F-V parameters revealed a higher reliability for the SJ90 compared to the SJpref (5.86% vs. 7.55%; CVratio = 1.29) with more pronounced differences using the FP (CVratio = 1.43) than the SAM procedure (CVratio = 1.14), and higher reliability for the SAM compared to the FP (6.14% vs. 7.27%; CVratio = 1.18). The SJpref and SAM procedures provided comparable or higher magnitude of the F-V relationship parameters than the SJ90 and FP, respectively. The three- and two-point methods revealed a comparable reliability and trivial differences in the magnitude of the F-V relationship parameters. The routine testing procedure of the F-V relationship could be simplified using the SJpref, the SAM procedure and the two-point method.


Subject(s)
Knee Joint/physiology , Plyometric Exercise , Weight-Bearing , Adult , Biomechanical Phenomena , Cross-Over Studies , Humans , Male , Range of Motion, Articular , Reproducibility of Results , Young Adult
16.
J Sports Sci ; 37(20): 2396-2402, 2019 Oct.
Article in English | MEDLINE | ID: mdl-31256708

ABSTRACT

This study aimed to (1) evaluate the shape of the force-velocity (F-V) relationship obtained from different muscles, (2) explore the concurrent validity of the two-point method with respect to the multiple-point method, (3) evaluate whether the F-V relationship can discriminate between muscle groups and genders, and (4) explore the generalisability of the same F-V relationship parameters (maximal force [F0], maximal velocity [V0]), and maximal power [P0]) between different tasks. The F-V relationship of 22 physically active participants (12 women) were tested during knee extension, knee flexion, elbow extension and elbow flexion through the multiple- (eight velocities: 30-60-90-120-150-180-210-240º/s) and two-point (two velocities: 60-180º/s) methods. The findings revealed (1) highly linear F-V relationships (r ≥ 0.893), (2) high concurrent validity of the two-point method for F0, but lower for V0 and P0, (3) the outcomes of both methods were sensitive to the muscle groups (higher for knee muscles) and gender (higher for men), and (4) the magnitude of the same F-V parameters were poorly correlated between different tasks (median r < 0.1). These results support the two-point method as a valid and sensitive procedure for determining the maximal capacities of the muscles to produce F, but not V, during isokinetic tests.


Subject(s)
Elbow/physiology , Exercise Test/methods , Knee/physiology , Muscle, Skeletal/physiology , Biomechanical Phenomena , Feasibility Studies , Female , Humans , Male , Reproducibility of Results , Sensitivity and Specificity , Sex Factors , Young Adult
17.
Nutr. hosp ; 36(2): 253-260, mar.-abr. 2019. tab, graf
Article in English | IBECS | ID: ibc-184315

ABSTRACT

Objectives: the aims of the study were to provide gender- and age-specific physical fitness levels among Serbian schoolchildren and to identify prevalence of overweight and obesity. Methods: a sample of 6,188 boys and 6,023 girls aged nine to 14 years were assessed using the physical fitness battery established through the National Fitness Project of Serbia. Physical fitness levels were determined for body height, body weight and body mass index and for six physical fitness tests (sit and reach, 4 x 10 m shuttle run, standing long jump, 30 sec sit-ups, bent arm hang, 20-m shuttle run). Centile smoothed curves for the 5rd, 25th, 50th, 75th and 95th percentiles were calculated using Cole’s LMS method. Prevalence of overweight and obesity was identified applying cut-off points for children (International Obesity Task Force). Results: the results revealed that anthropometric measures were higher in boys than in girls. In addition, boys had better physical fitness levels for all tests except for the sit and reach test, where girls performed slightly better. The overall prevalence of overweight and obesity amounts to 24.8% (19.8% overweight and 5% obese). With respect to gender, the prevalence of overweight and obesity was higher in boys (27%) compared to girls (22.4%). Conclusion: the presented data are the most up-to-date gender- and age-specific physical fitness levels for Serbian schoolchildren aged 9-14 years. The findings regarding prevalence in overweight and obesity indicated an alarming trend when compared to similar data from other similar studies (in European countries)


Objetivos: los objetivos del estudio fueron evaluar los niveles de condición física diferenciados por sexo y edad de estudiantes de escuela primaria de Serbia e identificar la prevalencia de sobrepeso y obesidad. Método: una muestra de 6.188 niños y 6.023 niñas de entre nueve y 14 años fueron evaluados mediante una batería de test físicos establecidos por el Proyecto Nacional de Condición Física de Serbia. Se evaluó la condición física mediante la altura, el peso, el índice de masa corporal y seis test físicos. Se calcularon curvas suavizadas para los percentiles 5, 25, 50, 75 y 95 usando el método de Cole. La prevalencia de sobrepeso y obesidad fue identificada aplicando los puntos de corte para niños (International Obesity Task Force). Resultados: los resultados revelaron medidas antropométricas mayores en niños que en niñas. Además, los niños tuvieron mejores niveles de condición física en todos los test, con la única excepción del sit and reach, que las niñas realizaron ligeramente mejor. La prevalencia de sobrepeso y obesidad fue del 24,8% (19,8% sobrepeso y 5% obesidad). Respecto al género, la prevalencia de sobrepeso y obesidad fue superior en los niños (27%) en comparación con las niñas (22,4%). Conclusión: los datos presentados son los más actualizados respecto a los niveles de condición física específicos para el género y la edad de niños estudiantes de Serbia de entre nueve y 14 años. Los hallazgos respecto a la prevalencia de sobrepeso y obesidad indican una tendencia alarmante frente a datos similares de otros estudios equivalentes (en países europeos)


Subject(s)
Humans , Male , Female , Child , Adolescent , Pediatric Obesity/epidemiology , Physical Fitness , Health Status , Anthropometry , Cross-Sectional Studies , Overweight/epidemiology , Prevalence , Serbia/epidemiology
18.
Nutr Hosp ; 36(2): 253-260, 2019 Apr 10.
Article in English | MEDLINE | ID: mdl-30834768

ABSTRACT

INTRODUCTION: Objectives: the aims of the study were to provide gender- and age-specific physical fitness levels among Serbian schoolchildren and to identify prevalence of overweight and obesity. Methods: a sample of 6,188 boys and 6,023 girls aged nine to 14 years were assessed using the physical fitness battery established through the National Fitness Project of Serbia. Physical fitness levels were determined for body height, body weight and body mass index and for six physical fitness tests (sit and reach, 4 x 10 m shuttle run, standing long jump, 30 sec sit-ups, bent arm hang, 20-m shuttle run). Centile smoothed curves for the 5rd, 25th, 50th, 75th and 95th percentiles were calculated using Cole's LMS method. Prevalence of overweight and obesity was identified applying cut-off points for children (International Obesity Task Force). Results: the results revealed that anthropometric measures were higher in boys than in girls. In addition, boys had better physical fitness levels for all tests except for the sit and reach test, where girls performed slightly better. The overall prevalence of overweight and obesity amounts to 24.8% (19.8% overweight and 5% obese). With respect to gender, the prevalence of overweight and obesity was higher in boys (27%) compared to girls (22.4%). Conclusion: the presented data are the most up-to-date gender- and age-specific physical fitness levels for Serbian schoolchildren aged 9-14 years. The findings regarding prevalence in overweight and obesity indicated an alarming trend when compared to similar data from other similar studies (in European countries).


INTRODUCCIÓN: Objetivos: los objetivos del estudio fueron evaluar los niveles de condición física diferenciados por sexo y edad de estudiantes de escuela primaria de Serbia e identificar la prevalencia de sobrepeso y obesidad. Método: una muestra de 6.188 niños y 6.023 niñas de entre nueve y 14 años fueron evaluados mediante una batería de test físicos establecidos por el Proyecto Nacional de Condición Física de Serbia. Se evaluó la condición física mediante la altura,el peso, el índice de masa corporal y seis test físicos. Se calcularon curvas suavizadas para los percentiles 5, 25, 50, 75 y 95 usando el método de Cole. La prevalencia de sobrepeso y obesidad fue identificada aplicando los puntos de corte para niños (International Obesity Task Force). Resultados: los resultados revelaron medidas antropométricas mayores en niños que en niñas. Además, los niños tuvieron mejores niveles de condición física en todos los test, con la única excepción del sit and reach, que las niñas realizaron ligeramente mejor. La prevalencia de sobrepeso y obesidad fue del 24,8% (19,8% sobrepeso y 5% obesidad). Respecto al género, la prevalencia de sobrepeso y obesidad fue superior en los niños (27%) en comparación con las niñas (22,4%). Conclusión: los datos presentados son los más actualizados respecto a los niveles de condición física específicos para el género y la edad de niños estudiantes de Serbia de entre nueve y 14 años. Los hallazgos respecto a la prevalencia de sobrepeso y obesidad indican una tendencia alarmante frente a datos similares de otros estudios equivalentes (en países europeos).


Subject(s)
Health Status , Pediatric Obesity/epidemiology , Physical Fitness , Adolescent , Anthropometry , Child , Cross-Sectional Studies , Female , Humans , Male , Overweight/epidemiology , Prevalence , Serbia/epidemiology
19.
J Strength Cond Res ; 32(11): 3267-3275, 2018 Nov.
Article in English | MEDLINE | ID: mdl-30540284

ABSTRACT

Petronijevic, MS, Garcia Ramos, A, Mirkov, DM, Jaric, S, Valdevit, Z, and Knezevic, OM. Self-preferred initial position could be a viable alternative to the standard squat jump testing procedure. J Strength Cond Res 32(11): 3267-3275, 2018-The purpose of this study was to compare both the magnitude and reliability of different variables (knee angle, squat depth, jump height [Hmax], maximum force [Fmax], and maximum power [Pmax]) between the standardized squat jump (SJ) and the SJ performed from the self-preferred position. Eleven team handball players (age: 19.5 ± 1.1 years; height: 1.88 ± 0.06 m; and body mass: 82.1 ± 8.7 kg) and 13 physically active students (age: 20.5 ± 0.9 years; height: 1.81 ± 0.06 m; and body mass: 76.6 ± 6.6 kg) were evaluated on 2 sessions during the standardized SJ (knee angle fixed at 90°) and the self-preferred SJ (self-selected knee angle to maximize Hmax). Two blocks of both 3 standardized SJ and 3 self-preferred SJ were performed on the first session, whereas only 1 block was performed in the second session. The squat depth was smaller for the self-preferred SJ, whereas the knee angle, Fmax, and Pmax were higher for the self-preferred SJ (p < 0.025). The magnitude of Hmax did not significantly differ between both jump types. Most importantly, the reliability of the mechanical outputs (Hmax, Fmax, and Pmax) was generally higher for the self-preferred SJ (9 of 12 comparisons), whereas only in 2 of 12 comparisons the reliability was meaningfully higher for the standardized SJ. No differences were observed between presumably more (handball players) and less skilled individuals (physically active subjects). These results suggest that the self-preferred SJ should be recommended over the standardized SJ (90° knee angle) because it is not only quicker and more ecologically valid, but could also provide the performance variables with higher reliability.


Subject(s)
Exercise Test , Knee Joint , Posture , Adolescent , Choice Behavior , Humans , Male , Reproducibility of Results , Sports , Young Adult
20.
Int J Sports Med ; 38(10): 741-746, 2017 Sep.
Article in English | MEDLINE | ID: mdl-28768340

ABSTRACT

Single outcomes of standard isokinetic dynamometry tests do not discern between various muscle mechanical capacities. In this study, we aimed to (1) evaluate the shape and strength of the force-velocity relationship of knee extensors, as observed in isokinetic tests conducted at a wide range of angular velocities, and (2) explore the concurrent validity of a simple 2-velocity method. Thirteen physically active females were tested for both the peak and averaged knee extensor concentric force exerted at the angular velocities of 30°-240°/s recorded in the 90°-170° range of knee extension. The results revealed strong (0.960

Subject(s)
Knee/physiology , Muscle Contraction/physiology , Muscle Strength Dynamometer , Muscle, Skeletal/physiology , Biomechanical Phenomena , Female , Humans , Knee Joint/physiology , Young Adult
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