Elsevier

Journal of Biomechanics

Volume 49, Issue 10, 5 July 2016, Pages 2047-2052
Journal of Biomechanics

Does weightlifting increase residual force enhancement?

https://doi.org/10.1016/j.jbiomech.2016.05.017Get rights and content

Abstract

The force maintained following stretching of an active muscle exceeds the isometric force at the same muscle length. This residual force enhancement (RFE) is different for various muscles. It is currently unknown whether training induces changes in RFE. Weightlifters perform a large number of eccentric contractions during training, and RFE might be functionally relevant. The aim of this study was to examine whether there is increased RFE in weightlifters versus a reference group.

Therefore, we measured external reaction forces during a multi-joint leg extension in weightlifters (n=10) and a reference group (n=11) using a motor driven leg press dynamometer (ISOMED 2000). Steady state isometric forces after stretching were compared to the corresponding forces obtained during isometric reference contractions. Statistical analyses yielded a significant RFE for both groups (p<0.001), but there were no RFE differences between the groups (p=0.320). However, RFE tends to decrease slower in the weightlifting group versus the reference group.

We conclude that long-term weightlifting has only a minor influence on RFE. We speculate that the specific training including a combination of eccentric and concentric exercises induced almost no changes in titin-isoform expression which may be responsible for generation of RFE after active muscle stretching.

Introduction

It has been known for more than 60 years that muscle force is enhanced (RFE, residual force enhancement) in the isometric phase following active stretching versus the isometric force at the corresponding muscle length (Abbott and Aubert, 1952). RFE has been detected at the myofibrillar level (Joumaa et al., 2008), in muscle fiber (Edman et al., 1982, Edman and Tsuchiya, 1996), in muscle (Abbott and Aubert, 1952, Siebert et al., 2015), and for multi-joint movements (Hahn et al., 2010). Furthermore, RFE has been observed during maximal (Hahn et al., 2010) and submaximal (Pinniger and Cresswell, 2007, Seiberl et al., 2012) muscle activation.

Muscles differ in the amount of RFE. Using the same experimental setup and conditions, Siebert et al. (2015) found muscle specific differences in 6 different rabbit shank muscles in the range of 8%–30% maximum isometric force (Fim). Hahn et al. (2007) observed no significant RFE in human quadriceps femoris muscle during maximum voluntary contraction (MVC). In contrast, RFE was reported to reach up to 25% Fim in several single and multi-joint movements (see Seiberl et al., 2015a, for review). For example, the RFE was confirmed for plantar flexion and dorsiflexion in the range of 7%–13% (Hahn et al., 2012, Pinniger and Cresswell, 2007, Tilp et al., 2011). Interestingly, RFE of dorsiflexors increased with age from about 8% in young (about 16 years) to 22% in old (about 76 years) people (Power et al., 2012).

The reasons for the observed differences in residual force enhancement are unclear. Differences may be attributed to different muscle functions and/or training. It is well known that muscles adapt e.g., architecture, fiber-tendon length ratio, and fiber type depending on their function (Biewener, 1998, Mörl et al., 2015, Roberts and Azizi, 2011, Rome et al., 1988). Moreover, among other strength training methods eccentric muscle training evokes gains in muscle strength and size (Hortobagyi et al., 1996, LaStayo et al., 2000). It apparently also results in increasing leg and muscle stiffness in humans trained on a high-force eccentric ergometer for 8 weeks (30 min three times per week) (Lindstedt et al., 2002). Additionally, an eccentrically trained group of basketball players increased their vertical jumping height versus a traditional strength/power resistance-training group. The differences were attributed to the higher leg stiffness and an increased storage and release of elastic energy (Lindstedt et al., 2001). The authors suggested that the protein titin may significantly contribute to the force production when the muscle actively lengthens and that titin may function as an adaptable muscle spring (Lindstedt et al., 2001, Lindstedt et al., 2002). In a study with rats, eccentric muscle training increased muscle stiffness during active muscle stretch, but this did not increase the rats’ maximum isometric force (Lindstedt et al., 2002). Increased muscle stiffness during stretching may be directly related to RFE (Rode et al., 2009, Till et al., 2010). Therefore, the ability of muscles to produce enhanced muscle stiffness and/or RFE might be a plastic feature of muscles depending on their use (Lindstedt et al., 2002, Rode et al., 2009).

The mechanisms of RFE are a matter of intense scientific debate (Campbell and Campbell, 2011, Edman, 2012, Siebert and Rode, 2014). While some researchers advocate mechanisms based on classic theories of contraction including half-sarcomere inhomogeneities (Morgan et al., 1982) and altered cross-bridge dynamics (Walcott and Herzog, 2008), others relate them to a non-crossbridge, semi-active contribution of titin to muscle force (Leonard and Herzog, 2010, Lindstedt et al., 2002, Nishikawa et al., 2012, Rode et al., 2009, Till et al., 2010). Indeed, titin-actin interactions seem to be a serious candidate to explain RFE (Herzog et al., 2015, Siebert and Rode, 2014).

There are a series of studies examining the impact of training and exercise on titin isoform expression. Titin content was reduced due to direct damage or degradation of titin following a single high-intensity eccentric resistance exercise of human M. vastus lateralis (Trappe et al., 2002). However, Lehti et al. (2009) reported no change in titin mRNA expression 2 days after fatiguing jumping exercise. Examination of muscle adaptation after training periods (8–15 weeks) including stretch-shortening exercises and explosive jump squat training resulted in no changes in titin isoforms (Kyrolainen et al., 2005, McGuigan et al., 2003). Interestingly, McBride at al. (2003) observed differential expression of titin isoforms in weight- and powerlifters in comparison to untrained non-athletic individuals. This might be an indication for training induced changes in RFE of weightlifters. However, none of the training or weightlifting studies focusing on changes in titin expression examined the influence of training on RFE.

Weightlifters perform many submaximal eccentric contractions in their training (e.g. squats with barbell loaded with 1.5–2.5 bodyweight). The relevance of RFE for stretch-shortening cycles of the human M. adductor pollicis was recently reported (Seiberl et al., 2015b) and RFE might be relevant in storing and releasing energy during squats, too. Furthermore, submaximal eccentric contractions might be sufficient to trigger RFE mechanisms, since RFE was observed for submaximal eccentric contractions (Pinniger and Cresswell, 2007, Seiberl et al., 2012). Therefore, we hypothesize that weightlifters exhibit RFE, and that the amount of RFE is higher than that of a reference group. To investigate this hypothesis we determined the RFE during maximal voluntary multi-joint leg extensions in a weightlifter and in a reference group, respectively, using a motor driven leg press dynamometer.

Section snippets

Subjects

We enrolled 21 subjects with no history of ankle, knee, or hip joint injury or neurological disorders. Free, written informed consent was obtained from all subjects and the study was conducted according to the latest Declaration of Helsinki. The weightlifter group (n=10, age: 26±5 years, weight: 94±18 kg, height: 178±5 cm) practiced weightlifting competitively (7 subjects in the highest German national league and 3 subjects in the Thuringia regional league). They trained on average 4 times per

Results

Residual force enhancement after stretch is illustrated for the individual subjects of the weightlifter and the reference group in Fig. 3. Statistical analyses yielded significant RFE for both groups (weightlifters and reference group) at all observed points in time (t1 to t3) (Intercept: F=24.0, p<0.001, ηP2=0.558) (Fig. 4). The mean RFE of the weightlifters at t1 (13.4% Fim, Fig. 5) was higher than the reference group (10.2% Fim). This slightly increased mean RFE of weightlifters was also

Discussion

We quantified the RFE of weightlifters in a functional relevant multi-joint movement similar to squats performed frequently during training. Although significant RFE was present in the weightlifting group, we found no significant differences versus the reference group.

Conflict of interest statement

The authors state that there are no conflicts of interest or future conflicts regarding this article.

Acknowledgment

This work was partially supported by the “Deutsche Forschungsgemeinschaft” (DFG Grant SI841/2-3 and SI841/6-1 to TS).

References (60)

  • O. Till et al.

    A mechanism accounting for independence on starting length of tension increase in ramp stretches of active skeletal muscle at short half-sarcomere lengths

    J. Theor. Biol.

    (2010)
  • S. Walcott et al.

    Modeling residual force enhancement with generic cross-bridge models

    Math. Biosci.

    (2008)
  • R. Yamasaki et al.

    Titin-actin interaction in mouse myocardium: passive tension modulation and its regulation by calcium/S100A1

    Biophys. J.

    (2001)
  • B.C. Abbott et al.

    The force exerted by active striated muscle during and after change of length

    J. Physiol.

    (1952)
  • A.A. Biewener

    Muscle function in vivo: a comparsion of muscles used for elastic energy storage savings versus muscles used to generate power

    Am. Zool.

    (1998)
  • S.G. Campbell et al.

    Mechanisms of residual force enhancement in skeletal muscle: insights from experiments and mathematical models

    Biophys. Rev.

    (2011)
  • J. Cohen

    StatistiCal Power Analysis for the Behavioral Sciences

    (1988)
  • L. Donath et al.

    Correct, fake and absent pre-information does not affect the occurrence and magnitude of the bilateral force deficit

    J Sport Sci. Med.

    (2014)
  • K.A. Edman

    Residual force enhancement after stretch in striated muscle. A consequence of increased myofilament overlap?

    J. Physiol.

    (2012)
  • K.A. Edman et al.

    Strain of passive elements during force enhancement by stretch in frog muscle fibres

    J. Physiol.

    (1996)
  • K.A. Edman et al.

    Enhancement of mechanical performance by stretch during tetanic contractions of vertebrate skeletal muscle fibres

    J. Physiol.

    (1978)
  • K.A. Edman et al.

    Residual force enhancement after stretch of contracting frog single muscle fibers

    J. Gen. Physiol.

    (1982)
  • S. Grimmer et al.

    Running on uneven ground: leg adjustment to vertical steps and self-stability

    J. Exp. Biol.

    (2008)
  • D. Hahn et al.

    Force enhancement during and following muscle stretch of maximal voluntarily activated human quadriceps femoris

    Eur. J. Appl. Physiol.

    (2007)
  • D. Hahn et al.

    Cortical and spinal excitability during and after lengthening contractions of the human plantar flexor muscles performed with maximal voluntary effort

    PLoS one

    (2012)
  • W. Herzog et al.

    A new paradigm for muscle contraction

    Front. Physiol.

    (2015)
  • T. Hortobagyi et al.

    Adaptive responses to muscle lengthening and shortening in humans

    J. Appl. Physiol.

    (1996)
  • A.F. Huxley et al.

    Structural changes in muscle during contraction; interference microscopy of living muscle fibres

    Nature

    (1954)
  • H. Huxley et al.

    Changes in the cross-striations of muscle during contraction and stretch and their structural interpretation

    Nature

    (1954)
  • V. Joumaa et al.

    Residual force enhancement in myofibrils and sarcomeres

    Proc. Biol. Sci.

    (2008)
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