International Journal of Environmental Research and Public Health

Research

7 pages, 769 KiB

Open AccessCommunication

Maximizing Acceleration and Change of Direction in Sport: A Case Series to Illustrate How the Force-Velocity Profile Provides Additional Information to That Derived from Linear Sprint Time

by Andrés Baena-Raya, Manuel A. Rodríguez-Pérez, Pedro Jiménez-Reyes and Alberto Soriano-Maldonado

Int. J. Environ. Res. Public Health 2021, 18(11), 6140; https://doi.org/10.3390/ijerph18116140 - 7 Jun 2021

Cited by 6 | Viewed by 5719

Abstract

Sprint running and change of direction (COD) present similar mechanical demands, involving an acceleration phase in which athletes need to produce and apply substantial horizontal external force. Assessing the mechanical properties underpinning individual sprint acceleration might add relevant information about COD performance in [...] Read more.

Sprint running and change of direction (COD) present similar mechanical demands, involving an acceleration phase in which athletes need to produce and apply substantial horizontal external force. Assessing the mechanical properties underpinning individual sprint acceleration might add relevant information about COD performance in addition to that obtained through sprint time alone. The present technical report uses a case series of three athletes with nearly identical 20 m sprint times but with different mechanical properties and COD performances. This makes it possible to illustrate, for the first time, a potential rationale for why the sprint force-velocity (FV) profile (i.e., theoretical maximal force (F₀), velocity (V₀), maximal power output (P_max), ratio of effective horizontal component (RF_peak) and index of force application technique (D_RF)) provides key information about COD performance (i.e., further to that derived from simple sprint time), which can be used to individualize training. This technical report provides practitioners with a justification to assess the FV profile in addition to sprint time when the aim is to enhance sprint acceleration and COD performance; practical interpretations and advice on how training interventions could be individualized based on the athletes’ differential sprint mechanical properties are also specified. Full article

(This article belongs to the Special Issue Use of Mechanical Variables to Prescribe Training and Evaluate Physical Fitness)

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12 pages, 960 KiB

Open AccessArticle

Isokinetic Testing: Sensitivity of the Force-Velocity Relationship Assessed through the Two-Point Method to Discriminate between Muscle Groups and Participants’ Physical Activity Levels

by Danica Janicijevic, Olivera M. Knezevic, Amador Garcia-Ramos, Danilo Cvetic and Dragan M. Mirkov

Int. J. Environ. Res. Public Health 2020, 17(22), 8570; https://doi.org/10.3390/ijerph17228570 - 19 Nov 2020

Cited by 8 | Viewed by 2909

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 [...] Read more.

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 [P_max]). Results: F₀ and P_max 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 P_max 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. Full article

(This article belongs to the Special Issue Use of Mechanical Variables to Prescribe Training and Evaluate Physical Fitness)

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10 pages, 740 KiB

Open AccessArticle

Group versus Individualised Minimum Velocity Thresholds in the Prediction of Maximal Strength in Trained Female Athletes

by Elias J. G. Caven, Tom J. E. Bryan, Amelia F. Dingley, Benjamin Drury, Amador Garcia-Ramos, Alejandro Perez-Castilla, Jorge Arede and John F. T. Fernandes

Int. J. Environ. Res. Public Health 2020, 17(21), 7811; https://doi.org/10.3390/ijerph17217811 - 26 Oct 2020

Cited by 16 | Viewed by 3024

Abstract

This study examined the accuracy of different velocity-based methods in the prediction of bench press and squat one-repetition maximum (1RM) in female athletes. Seventeen trained females (age 17.8 ± 1.3 years) performed an incremental loading test to 1RM on bench press and squat [...] Read more.

This study examined the accuracy of different velocity-based methods in the prediction of bench press and squat one-repetition maximum (1RM) in female athletes. Seventeen trained females (age 17.8 ± 1.3 years) performed an incremental loading test to 1RM on bench press and squat with the mean velocity being recorded. The 1RM was estimated from the load–velocity relationship using the multiple- (8 loads) and two-point (2 loads) methods and group and individual minimum velocity thresholds (MVT). No significant effect of method, MVT or interaction was observed for the two exercises (p > 0.05). For bench press and squat, all prediction methods demonstrated very large to nearly perfect correlations with respect to the actual 1RM (r range = 0.76 to 0.97). The absolute error (range = 2.1 to 3.8 kg) for bench press demonstrated low errors that were independent of the method and MVT used. For squat, the favorable group MVT errors for the multiple- and two-point methods (absolute error = 7.8 and 9.7 kg, respectively) were greater than the individual MVT errors (absolute error = 4.9 and 6.3 kg, respectively). The 1RM can be accurately predicted from the load–velocity relationship in trained females, with the two-point method offering a quick and less fatiguing alternative to the multiple-point method. Full article

(This article belongs to the Special Issue Use of Mechanical Variables to Prescribe Training and Evaluate Physical Fitness)

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12 pages, 2643 KiB

Open AccessArticle

Temporal Kinematic Differences between Forward and Backward Jump-Landing

by Datao Xu, Xuanzhen Cen, Meizi Wang, Ming Rong, Bíró István, Julien S. Baker and Yaodong Gu

Int. J. Environ. Res. Public Health 2020, 17(18), 6669; https://doi.org/10.3390/ijerph17186669 - 13 Sep 2020

Cited by 23 | Viewed by 2685

Abstract

Backward jump-landing during sports performance will result in dynamic postural instability with a greater risk of injury, and most research studies have focused on forward landing. Differences in kinematic temporal characteristics between single-leg and double-leg backward jump-landing are seldom researched and understood. The [...] Read more.

Backward jump-landing during sports performance will result in dynamic postural instability with a greater risk of injury, and most research studies have focused on forward landing. Differences in kinematic temporal characteristics between single-leg and double-leg backward jump-landing are seldom researched and understood. The purpose of this study was to compare and analyze lower extremity kinematic differences throughout the landing phases of forward and backward jumping using single-leg and double-leg landings (FS and BS, FD and BD). Kinematic data were collected during the landing phases of FS and BS, FD and BD in 45 participants. Through statistical parametric mapping (SPM) analysis, we found that the BS showed smaller hip and knee flexion and greater vertical ground reactive force (VGRF) than the FS during 0–37.42% (p = 0.031), 16.07–32.11% (p = 0.045), and 23.03–17.32% (p = 0.041) landing phases. The BD showed smaller hip and knee flexion than the FD during 0–20.66% (p = 0.047) and 0–100% (p < 0.001) landing phases. Most differences appeared within a time frame during the landing phase at 30–50 ms in which non-contact anterior cruciate ligament (ACL) injuries are thought to occur and are consistent with the identification of risk in biomechanical analysis. A landing strategy that consciously increases the knee and hip flexion angles during backward landing should be considered for people as a measure to avoid injury during the performance of this type of physical activity. Full article

(This article belongs to the Special Issue Use of Mechanical Variables to Prescribe Training and Evaluate Physical Fitness)

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11 pages, 316 KiB

Open AccessArticle

Velocity Loss Thresholds Reliably Control Kinetic and Kinematic Outputs during Free Weight Resistance Training

by Madison Pearson, Amador García-Ramos, Matthew Morrison, Carlos Ramirez-Lopez, Nicholas Dalton-Barron and Jonathon Weakley

Int. J. Environ. Res. Public Health 2020, 17(18), 6509; https://doi.org/10.3390/ijerph17186509 - 7 Sep 2020

Cited by 7 | Viewed by 3187

Abstract

Exercise velocity and relative velocity loss thresholds (VLTs) are commonly used in velocity-based resistance training. This study aims to quantify the between-day reliability of 10%, 20%, and 30% VLTs on kinetic and kinematic outputs, changes in external load, and repetition characteristics in well-trained [...] Read more.

Exercise velocity and relative velocity loss thresholds (VLTs) are commonly used in velocity-based resistance training. This study aims to quantify the between-day reliability of 10%, 20%, and 30% VLTs on kinetic and kinematic outputs, changes in external load, and repetition characteristics in well-trained athletes. Using a repeated, counter-balanced crossover design, twelve semi-professional athletes completed five sets of the back squat with an external load corresponding to a mean concentric velocity of ~0.70 m·s⁻¹ and a VLT applied. The testing sessions were repeated after four weeks of unstructured training to assess the long-term reliability of each VLT. A coefficient of variation (CV) <10% was used to classify outputs as reliable. Kinetic and kinematic outputs and external load were largely reliable, with only peak power during sets 2–5 within the 10% VLT condition demonstrating a CV >10% (CV: 11.14–14.92%). Alternatively, the repetitions completed within each set showed large variation (CV: 18.92–67.49%). These findings demonstrate that by utilizing VLTs, kinetic and kinematic outputs can be prescribed and replicated across training mesocycles. Thus, for practitioners wishing to reliably control the kinetic and kinematic stimulus that is being applied to their athletes, it is advised that a velocity-based approach is used. Full article

(This article belongs to the Special Issue Use of Mechanical Variables to Prescribe Training and Evaluate Physical Fitness)

11 pages, 765 KiB

Open AccessArticle

by Dragan M. Mirkov, Olivera M. Knezevic, Amador Garcia-Ramos, Milan Čoh and Nejc Šarabon

Int. J. Environ. Res. Public Health 2020, 17(18), 6447; https://doi.org/10.3390/ijerph17186447 - 4 Sep 2020

Cited by 7 | Viewed by 3634

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 [...] Read more.

(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 P_max (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 P_max 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. Full article

(This article belongs to the Special Issue Use of Mechanical Variables to Prescribe Training and Evaluate Physical Fitness)

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12 pages, 1039 KiB

Open AccessArticle

Effect of a Combined Program of Strength and Dual Cognitive-Motor Tasks in Multiple Sclerosis Subjects

by Carmen Gutiérrez-Cruz, F.Javier Rojas-Ruiz, Juan Carlos De la Cruz-Márquez and Marcos Gutiérrez-Dávila

Int. J. Environ. Res. Public Health 2020, 17(17), 6397; https://doi.org/10.3390/ijerph17176397 - 2 Sep 2020

Cited by 9 | Viewed by 6219

Abstract

This study investigated the effects of a 24-week combined training program (CTP) based on strength exercises and cognitive–motor tasks performed concurrently in participants with multiple sclerosis. A randomized, controlled intervention study was carried out. In total, 31 subjects with a confirmed diagnosis of [...] Read more.

This study investigated the effects of a 24-week combined training program (CTP) based on strength exercises and cognitive–motor tasks performed concurrently in participants with multiple sclerosis. A randomized, controlled intervention study was carried out. In total, 31 subjects with a confirmed diagnosis of multiple sclerosis (14 men and 17 women) were stratified and randomized into an intervention group (17 subjects) and a control group (14 subjects). The intervention group completed three weekly training sessions for 24 weeks, while the control group pursued their normal daily activities. In this program, cognitive–motor tasks were completed at once (dual tasking). A 3D photogrammetry connected to a selective attention system designed for dual tasking while walking was used. Ground reaction forces were measured using two force plates, one for sit-to-stand testing, while the other was used for static force measurement. Postural equilibrium was examined using a stabilometric plate based for Romberg test assessment. The 24-week training program for multiple sclerosis patients improved their static peak force by 11% (p < 0 .05), their rate of force development by 36% (p < 0.05), and their balance (p < 0.05). Performance in daily activities such as walking or sitting-to-standing improved significantly in multiple sclerosis participants. CTP training was effective in reducing the dual-task costs of step length (48%) and walking velocity (54%), as compared to a matched control group. Full article

(This article belongs to the Special Issue Use of Mechanical Variables to Prescribe Training and Evaluate Physical Fitness)

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11 pages, 857 KiB

Open AccessArticle

Different Movement Strategies in the Countermovement Jump Amongst a Large Cohort of NBA Players

by Jacob Rauch, Eric Leidersdorf, Trent Reeves, Leah Borkan, Marcus Elliott and Carlos Ugrinowitsch

Int. J. Environ. Res. Public Health 2020, 17(17), 6394; https://doi.org/10.3390/ijerph17176394 - 2 Sep 2020

Cited by 16 | Viewed by 10191

Abstract

Previous research has demonstrated large amounts of inter-subject variability in downward (unweighting & braking) phase strategies in the countermovement jump (CMJ). The purpose of this study was to characterize downward phase strategies and associated temporal, kinematic and kinetic CMJ variables. One hundred and [...] Read more.

Previous research has demonstrated large amounts of inter-subject variability in downward (unweighting & braking) phase strategies in the countermovement jump (CMJ). The purpose of this study was to characterize downward phase strategies and associated temporal, kinematic and kinetic CMJ variables. One hundred and seventy-eight NBA (National Basketball Association) players (23.6 ± 3.7 years, 200.3 ± 8.0 cm; 99.4 ± 11.7 kg; CMJ height 68.7 ± 7.4 cm) performed three maximal CMJs. Force plate and 3D motion capture data were integrated to obtain kinematic and kinetic outputs. Afterwards, athletes were split into clusters based on downward phase characteristics (k-means cluster analysis). Lower limb joint angular displacement (i.e., delta flexion) explained the highest portion of point variability (89.3%), and three clusters were recommended (Ball Hall Index). Delta flexion was significantly different between clusters and players were characterized as “stiff flexors”, “hyper flexors”, or “hip flexors”. There were no significant differences in jump height between clusters (p > 0.05). Multiple regression analyses indicated that most of the jumping height variance was explained by the same four variables, (i.e., sum concentric relative force, knee extension velocity, knee extension acceleration, and height) regardless of the cluster (p < 0.05). However, each cluster had its own unique set of secondary predictor variables. Full article

(This article belongs to the Special Issue Use of Mechanical Variables to Prescribe Training and Evaluate Physical Fitness)

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