Resistance Training for the Maximization of the Horizontal Force Production

To train hamstring muscle specifically to sprint, strengthening programs should target exercises associated with horizontal force production and high levels of hamstring activity. Therefore, the objectives of this study were to analyze the correlation between force production capacities during sprinting and hamstring strengthening exercises, and to compare hamstring muscle activity during sprinting and these exercises. Fourteen track and field regional level athletes performed two maximal 50-m sprints and six strengthening exercises: Nordic hamstring exercises without and with hip flexion, Upright-hip-extension in isometric and concentric modalities, Standing kick, and Slide-leg-bridge. The sprinting horizontal force production capacity at low (F0) and high (V0) speeds was computed from running velocity data. Hamstring muscle performances were assessed directly or indirectly during isolated exercises. Hamstring muscle electromyographic activity was recorded during all tasks. Our results demonstrate substantially large to very large correlations between V0 and performances in the Upright-hip-extension in isometric (rs = 0.56; p = 0.040), Nordic hamstring exercise without hip flexion (rs = 0.66; p = 0.012) and with 90° hip flexion (rs = 0.73; p = 0.003), and between F0 and Upright-hip-extension in isometric (rs = 0.60; p = 0.028) and the Nordic hamstring exercise without hip flexion (rs = 0.59; p = 0.030). However, none of the test exercises activated hamstring muscles more than an average of 60% of the maximal activation during top-speed sprinting. In conclusion, training programs aiming to be sprint-specific in terms of horizontal force production could include exercises such as the Upright-hip-extension and the Nordic hamstring exercise, in addition to maximal sprinting activity, which is the only exercise leading to high levels of hamstring muscle activity.

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Maintenance of ankle power and decreased inter-limb asymmetry during sprint running in fatigued multi-speed athletes

10.1101/2021.10.17.464459 ◽

2021 ◽

Author(s):

Shayne Vial ◽

Jodie Cochrane Wilkie ◽

Mitchell Turner ◽

Anthony J Blazevich

Keyword(s):

Injury Risk ◽

Reaction Force ◽

Force Production ◽

Knee Joints ◽

Horizontal Force ◽

Running Speed ◽

Sprint Running ◽

Limb Asymmetry ◽

Hip Flexion ◽

Distal Joint

The ability to shift from walking and jogging to sprinting gaits, even when fatigued after prolonged effort, would have been as useful to our hunter-gatherer ancestors as it is in modern day sports. During prolonged jogging, joint moment and work are reduced in the distal (ankle) joint but increased at proximal (hip/knee) joints as fatigue progresses, and might be expected to occur in sprinting. Fatigue is also thought to increase inter-limb kinematic and force production asymmetries, which are speculated to influence injury risk. However, the effects of running-related fatigue on sprint running gait have been incompletely studied, so these hypotheses remain untested. We studied 3-D kinematics and ground reaction force production in dominant (DL) and non-dominant (NDL) legs during both non-fatigued and fatigue sprinting in habitual but uncoached running athletes. Contrary to the tested hypotheses, relative between-leg differences were greater in non-fatigued than fatigued sprinting. When not fatigued, DL produced greater propulsive impulse through both greater positive and negative work being performed at the ankle, whilst NDL produced more vertical impulse, possibly resulting from the greater hip flexion observed prior to the downwards acceleration of the foot towards the ground. Whilst few changes were detected in DL once fatigued, NDL shifted towards greater horizontal force production, largely resulting from an increase in plantarflexion (distal-joint) moments and power. After fatiguing running, therefore, inter-limb asymmetry was reduced and no distal-to-proximal shift in work/power was detected during sprinting. Speculatively, these adaptations may help to attenuate decreases in running speed whilst minimising injury risk.

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Impairment of Sprint Mechanical Properties in an Actual Soccer Match: A Pilot Study

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2015-0567 ◽

2016 ◽

Vol 11 (7) ◽

pp. 893-898 ◽

Cited By ~ 20

Author(s):

Ryu Nagahara ◽

Jean-Benoit Morin ◽

Masaaki Koido

Keyword(s):

Mechanical Properties ◽

High Speed ◽

Force Production ◽

Maximal Velocity ◽

Horizontal Force ◽

Time Data ◽

Long Distance ◽

Soccer Match ◽

Long Distance Running ◽

Before And After

Purpose:To assess soccer-specific impairment of mechanical properties in accelerated sprinting and its relation with activity profiles during an actual match.Methods:Thirteen male field players completed 4 sprint measurements, wherein running speed was obtained using a laser distance-measurement system, before and after the 2 halves of 2 soccer matches. Macroscopic mechanical properties (theoretical maximal horizontal force [F0], maximal horizontal sprinting power [Pmax], and theoretical maximal sprinting velocity [V0]) during the 35-m sprint acceleration were calculated from speed–time data. Players’ activity profiles during the matches were collected using global positioning system units.Results:After the match, although F0 and Pmax did not significantly change, V0 was reduced (P = .038), and the magnitude of this reduction correlated with distance (positive) and number (negative) of high-speed running, number of running (negative), and other low-intensity activity distance (negative) during the match. Moreover, Pmax decreased immediately before the second half (P = .014).Conclusions:The results suggest that soccer-specific fatigue probably impairs players’ maximal velocity capabilities more than their maximal horizontal force-production abilities at initial acceleration. Furthermore, long-distance running, especially at high speed, during the match may induce relatively large impairment of maximal velocity capabilities. In addition, the capability of producing maximal horizontal power during sprinting is presumably impaired during halftime of a soccer match with passive recovery. These findings could be useful for players and coaches aiming to train effectively to maintain sprinting performance throughout a soccer match when planning a training program.

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Assessing Horizontal Force Production in Resisted Sprinting: Computation and Practical Interpretation

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2018-0578 ◽

2019 ◽

Vol 14 (5) ◽

pp. 689-693 ◽

Cited By ~ 2

Author(s):

Matt R. Cross ◽

Farhan Tinwala ◽

Seth Lenetsky ◽

Scott R. Brown ◽

Matt Brughelli ◽

...

Keyword(s):

Performance Enhancement ◽

Force Production ◽

Test Case ◽

Horizontal Force ◽

Sprint Training ◽

Field Methods ◽

Potential Methods ◽

Training Apparatus ◽

The Impact ◽

Resisted Sprinting

The assessment of horizontal force during overground sprinting is increasingly prevalent in practice and research, stemming from advances in technology and access to simplified yet valid field methods. As researchers search out optimal means of targeting the development of horizontal force, there is considerable interest in the effectiveness of external resistance. Increasing attention in research provides more information surrounding the biomechanics of sprinting in general and insight into the potential methods of developing determinant capacities. However, there is a general lack of consensus on the assessment and computation of horizontal force under resistance, which has resulted in a confusing narrative surrounding the practical applicability of loading parameters for performance enhancement. As such, the aim of this commentary was twofold: to provide a clear narrative of the assessment and computation of horizontal force in resisted sprinting and to clarify and discuss the impact of methodological approaches to subsequent training implementation. Horizontal force computation during resisted sleds, a common sprint-training apparatus in the field, is used as a test case to illustrate the risks associated with substandard methodological practices and improperly accounting for the effects of friction. A practical and operational synthesis is provided to help guide researchers and practitioners in selecting appropriate resistance methods. Finally, an outline of future challenges is presented to aid the development of these approaches.

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Very-Heavy Sled Training for Improving Horizontal-Force Output in Soccer Players

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2016-0444 ◽

2017 ◽

Vol 12 (6) ◽

pp. 840-844 ◽

Cited By ~ 41

Author(s):

Jean-Benoît Morin ◽

George Petrakos ◽

Pedro Jiménez-Reyes ◽

Scott R. Brown ◽

Pierre Samozino ◽

...

Keyword(s):

Body Mass ◽

Effect Size ◽

Reaction Force ◽

Force Production ◽

Sprint Performance ◽

Soccer Players ◽

Control Group ◽

Horizontal Force ◽

Sprint Training ◽

Practical Applications

Background:Sprint running acceleration is a key feature of physical performance in team sports, and recent literature shows that the ability to generate large magnitudes of horizontal ground-reaction force and mechanical effectiveness of force application are paramount. The authors tested the hypothesis that very-heavy loaded sled sprint training would induce an improvement in horizontal-force production, via an increased effectiveness of application.Methods:Training-induced changes in sprint performance and mechanical outputs were computed using a field method based on velocity–time data, before and after an 8-wk protocol (16 sessions of 10- × 20-m sprints). Sixteen male amateur soccer players were assigned to either a very-heavy sled (80% body mass sled load) or a control group (unresisted sprints).Results:The main outcome of this pilot study is that very-heavy sled-resisted sprint training, using much greater loads than traditionally recommended, clearly increased maximal horizontal-force production compared with standard unloaded sprint training (effect size of 0.80 vs 0.20 for controls, unclear between-groups difference) and mechanical effectiveness (ie, more horizontally applied force; effect size of 0.95 vs –0.11, moderate between-groups difference). In addition, 5-m and 20-m sprint performance improvements were moderate and small for the very-heavy sled group and small and trivial for the control group, respectively.Practical Applications:This brief report highlights the usefulness of very-heavy sled (80% body mass) training, which may suggest value for practical improvement of mechanical effectiveness and maximal horizontal-force capabilities in soccer players and other team-sport athletes.Results:This study may encourage further research to confirm the usefulness of very-heavy sled in this context.

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The knowns and unknowns of neural adaptations to resistance training

European Journal of Applied Physiology ◽

10.1007/s00421-020-04567-3 ◽

2020 ◽

Author(s):

Jakob Škarabot ◽

Callum G. Brownstein ◽

Andrea Casolo ◽

Alessandro Del Vecchio ◽

Paul Ansdell

Keyword(s):

Resistance Training ◽

Motor Unit ◽

Force Production ◽

Intracortical Inhibition ◽

Short Term ◽

Neural Adaptations ◽

Non Invasive ◽

Reticulospinal Tract ◽

Large Motor ◽

Potential Substrate

AbstractThe initial increases in force production with resistance training are thought to be primarily underpinned by neural adaptations. This notion is firmly supported by evidence displaying motor unit adaptations following resistance training; however, the precise locus of neural adaptation remains elusive. The purpose of this review is to clarify and critically discuss the literature concerning the site(s) of putative neural adaptations to short-term resistance training. The proliferation of studies employing non-invasive stimulation techniques to investigate evoked responses have yielded variable results, but generally support the notion that resistance training alters intracortical inhibition. Nevertheless, methodological inconsistencies and the limitations of techniques, e.g. limited relation to behavioural outcomes and the inability to measure volitional muscle activity, preclude firm conclusions. Much of the literature has focused on the corticospinal tract; however, preliminary research in non-human primates suggests reticulospinal tract is a potential substrate for neural adaptations to resistance training, though human data is lacking due to methodological constraints. Recent advances in technology have provided substantial evidence of adaptations within a large motor unit population following resistance training. However, their activity represents the transformation of afferent and efferent inputs, making it challenging to establish the source of adaptation. Whilst much has been learned about the nature of neural adaptations to resistance training, the puzzle remains to be solved. Additional analyses of motoneuron firing during different training regimes or coupling with other methodologies (e.g., electroencephalography) may facilitate the estimation of the site(s) of neural adaptations to resistance training in the future.

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