Load knowledge reduces rapid force production and muscle activation during maximal-effort concentric lifts

Hernández-Davó, José Luis; Solana, Rafael Sabido; Moya‐Ramón, Manuel; Blazevich, Anthony J.

doi:10.1007/s00421-015-3276-8

Cited by 15 publications

(18 citation statements)

References 42 publications

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“…Contrary to our findings, there are also studies that found significantly increased muscular activities during PRE in unknown vs. known loading conditions . Pre‐activation and stiffness were higher in a rebound (SSC) bench press condition where the load was not known compared with where the load was known . In addition, EMG activities were increased during PRE when unknown loads were provided .…”

Section: Discussioncontrasting

confidence: 99%

Anticipation of drop height affects neuromuscular control and muscle‐tendon mechanics

Helm

Freyler

Waldvogel

et al. 2019

Scandinavian Med Sci Sports

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This study examined the effect of drop height on neuromechanical control of the plantarflexors in drop jumps (DJs) before and during ground contact (GC). The effect of anticipation on muscle mechanical configurations was investigated in 22 subjects in three conditions (20, 30, and 40 cm): (i) known, (ii) unknown, or (iii) cheat falling heights (announced 40 cm, but actual drop height was 20 cm). Electromyographic (EMG) activity of the m. gastrocnemius medialis (GM) and other shank muscles was recorded and analyzed before GC and during GC separately for the short-, medium-, and long-latency responses (SLR, MLR, and LLR). Changes in GM fascicle length (L M ) were determined via B-mode ultrasound, and muscle-tendon unit length (L MTU ) was estimated. Peak force (P < .001), rate of force development (RFD) (P = .001) and GM EMG activity prior to (P = .003) and during GC (P = .007) was reduced in the unknown compared with the known conditions (P < .05). The amount of shortening in L MTU during GC in unknown and cheat was less compared with the known conditions (P = .005; P = .049). Changes in L MTU lengthening negatively correlatedwith changes in GM activity around SLR and MLR (P = .006; P = .02) in known and unknown conditions. Taken together, it seems that the central nervous system applies a protective strategy in the unknown condition by reducing muscle activity to result in a lower muscular stiffness and increased tendinous lengthening prior to and during GC. This might be a mechanism to absorb greater elastic energy in the tendon and reduce the magnitude and rate of muscle lengthening and subsequent stretch-induced muscle damage.

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Section: Discussioncontrasting

confidence: 99%

Anticipation of drop height affects neuromuscular control and muscle‐tendon mechanics

Helm

Freyler

Waldvogel

et al. 2019

Scandinavian Med Sci Sports

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“…The mechanism by which the use of unknown loads supposes a greater stimulus to the central nervous system may be due to a possible overestimation of the weight, causing a larger force production than that required to move the real mass [ 28 ].Our results are in accordance with the acute studies, showing that the UL group improved to a larger extent when compared to the KL group (UL: + 14.3–33.7%; KL: 8.2–21.1%) in the power developed in the early time intervals (< 150 ms). The mechanisms underlying the greater improvements of the UL group could be explained by the subject’s response to lifting unknown loads, which has been previously reported as increased EMG response in pectoralis major and anterior deltoid muscles in the early time intervals before and after the movement onset [ 27 ], which is in agreement with the increases shown by several authors in muscle activation and movement velocities when using unknown loads compared with known loads [ 17 , 29 ]. The increases in power output in the early time intervals of the movement may be explained by both an increase in motor unit firing frequency [ 30 ], and increases in motor unit recruitment due to are duced recruitment threshold of the motor units [ 31 ].…”

Section: Discussionsupporting

confidence: 83%

“…150 ms) of a movement. It has been reported that both a greater power output and muscle activation can be produced at early time intervals as an acute response of using unknown loads, when compared to known loads [ 13 , 27 ]. The mechanism by which the use of unknown loads supposes a greater stimulus to the central nervous system may be due to a possible overestimation of the weight, causing a larger force production than that required to move the real mass [ 28 ].Our results are in accordance with the acute studies, showing that the UL group improved to a larger extent when compared to the KL group (UL: + 14.3–33.7%; KL: 8.2–21.1%) in the power developed in the early time intervals (< 150 ms).…”

Section: Discussionmentioning

confidence: 99%

Effects of 4-Week Training Intervention with Unknown Loads on Power Output Performance and Throwing Velocity in Junior Team Handball Players

et al. 2016

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PurposeTo compare the effect of 4-week unknown vs known loads strength training intervention on power output performance and throwing velocity in junior team handball players.MethodsTwenty-eight junior team-handball players (17.2 ± 0.6 years, 1.79 ± 0.07 m, 75.6 ± 9.4 kg)were divided into two groups (unknown loads: UL; known loads: KL). Both groups performed two sessions weekly consisting of four sets of six repetitions of the bench press throw exercise, using the 30%, 50% and 70% of subjects’ individual 1 repetition maximum (1RM). In each set, two repetitions with each load were performed, but the order of the loads was randomised. In the KL group, researchers told the subjects the load to mobilise prior each repetition, while in the UL group, researchers did not provide any information. Maximal dynamic strength (1RM bench press), power output (with 30, 50 and 70% of 1RM) and throwing velocity (7 m standing throw and 9 m jumping throw) were assessed pre- and post-training intervention.ResultsBoth UL and KL group improved similarly their 1RM bench press as well as mean and peak power with all loads. There were significant improvements in power developed in all the early time intervals measured (150 ms) with the three loads (30, 50, 70% 1RM) in the UL group, while KL only improved with 30% 1RM (all the time intervals) and with 70% 1RM (at certain time intervals). Only the UL group improved throwing velocity in both standing (4.7%) and jumping (5.3%) throw (p > 0.05).ConclusionsThe use of unknown loads has led to greater gains in power output in the early time intervals as well as to increases in throwing velocity compared with known loads. Therefore unknown loads are of significant practical use to increase both strength and in-field performance in a short period of training.

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“…Instructions for training such as very heavy (strength-oriented), intermediate (Pmax), or very light (speed-oriented) may be a sufficient prescription, rather than aiming for precise intensity values. A recent study by Hernandez-Davo et al (2015) 72) demonstrated that lifting of unknown loads resulted in more rapid force production and greater EMG activity than those of lifting the same loads with load knowledge, despite an instruction to elicit maximum effort. It was suggested that an over-estimation of the load resulting from no-load knowledge increased the pre-programmed muscle activation (or activation preparation).…”

Section: Summary and Implicationsmentioning

confidence: 99%

Strategies for maximizing power and strength gains in isoinertial resistance training: Implications for competitive athletes

Sakamoto

Sinclair

Naito

2016

JPFSM

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Isoinertial resistance is imposed during natural human dynamics, where muscles contract at varying velocities and joint angles. In many sports, the ability to produce greater force at faster speed is essential for successful outcomes. Hence, power training under isoinertial resistance (e.g., body mass, weights or flywheel, etc.) provides event-specific adaptive stimuli. Conventional power training consists of a combination of strength-oriented (> 70% 1RM) and speed-oriented (< 30% 1RM, e.g., plyometrics) methods, with the aim of being able to overcome variable external loadings across a range of velocities. An alternative maximum power output training (Pmax training, 30-70% 1RM) has been found to elicit equivalent or greater effectiveness compared to the conventional methods. It is, however, difficult to precisely reproduce the prescribed intensities, given several concerns associated with 1RM testing and the variable accuracies of the repetition-intensity or velocity-intensity relationship. No matter what level of resistance is assigned to an exercise, it is far more important to exert as much effort (or fastest concentric speed) as possible per repetition, otherwise, the training effects are reduced. At light intensities, however, a large portion of the concentric phase is spent in deceleration for the subsequent phase transition, which may limit effort. Making projectile motions, therefore, are necessary. The utilization of stretch-shortening cycle effects, with increased power ability, may give a further training edge. Coaches and trainees should be aware that successful movements in power training are defined as greater acceleration, speed and displacement for every repetition, rather than simply neat form or smooth repetitiveness.

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Load knowledge reduces rapid force production and muscle activation during maximal-effort concentric lifts

Cited by 15 publications

References 42 publications

Anticipation of drop height affects neuromuscular control and muscle‐tendon mechanics

Anticipation of drop height affects neuromuscular control and muscle‐tendon mechanics

Effects of 4-Week Training Intervention with Unknown Loads on Power Output Performance and Throwing Velocity in Junior Team Handball Players

Strategies for maximizing power and strength gains in isoinertial resistance training: Implications for competitive athletes

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