**1. Introduction**

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The musculoskeletal injuries, both acute and chronic, are very common in sport activities accounting from 10% to 55% of all injuries and often results in prolonged rehabilitation and time out from competition (Garrett, 1996; Croisier et al.,2002). Their treatment is a challenge for all health care professionals, which are involved in the management of rehabilitation and return sporting activities of the athletes. Usually, skeletal muscle injuries are common in professional and amateur athletes. Muscle injuries often occur with over 90% caused by excessive strain or by contusion (Järvinen et al., 2005) and may result in the inability to train or compete for several weeks and have a high tendency to recur (Verrall et al., 2001; Orchard and Best, 2002). A 5-year study of European soccer players showed that muscle strain repre‐ sented 30% of injuries. Among these, those of quadriceps (32%), hamstring (28%), adductor (19%), and gastrocnemius (12%) were the most common (Volpi et al., 2004).

It has been showed that injured muscles can initiate regeneration promptly, but the healing process is often inefficient and hindered by the formation of scar tissue, which may contribute to muscle re-injury (Huard et al., 2002).

The first step in the muscle injuries management is to be able to answer questions that are often asked to physician or physical therapist by the injured athlete: "How long will it take to recover?"; "When can I return to the field?". However, answer to these questions is very difficult because it depend on age, activity level of injured athlete, and by pressure of coaches, parents, managers and media, etc. Unfortunately, until today, the answers to these questions are based on personal experience rather than on clinical evidences.

© 2013 Foglia et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The management of muscle injuries, despite the lack of high quality studies, can be improved with the knowledge of the possible mechanisms that cause muscle injuries (Ekstrand et al., 1983), and with the identification of risk factors associated with injury occurrence (Verrall et al., 2003; Brockett et al., 2004). Acquisition of these knowledge will lead to an improvement of our preventive, therapeutic and rehabilitative strategies (Gibbs et al., 2004; Cross et al., 2004; Orchard and Best, 2002; Sherry and Best, 2004; Cacchio et al, 2006) for a safe return to sport activities.

Generally, the risk factors for injury are divided into intrinsic (athlete related) and extrinsic (environment-related) (Inklaar, 1994; Taimela et al., 1990). Among the intrinsic factors most frequently identified by prospective studies are: age (Gabbe et al., 2006), fatigue (Greig and Siegler, 2009), a history of previous injury (Hagglund et al., 2006; Gabbe et al., 2010), postural and biomechanical deficits (Agre, 1985), lack of extensibility, and imbalance of agonist/ antagonist muscular strength and power ratio (Askling et al., 2003; Croisier et al., 2008).

Conservative Treatment of Muscle Injuries: From Scientific Evidence to Clinical Practice

http://dx.doi.org/10.5772/56550

171

Among the extrinsic factors, importance is attributed to inadequate warm-up, climatic factors, inadequate training, playground surface, inadequate sports equipment (Hawkins and Fuller,

Orchard and colleagues suggested that intrinsic factors are more predictive of a muscle injury than extrinsic factors. However, a recent systematic review concluded that no single risk factor (intrinsic or extrinsic) showed a significant correlation with hamstring muscles injuries (Foreman et al., 2006). For this reason, as mentioned above the multifactorial etiology of muscle

The prevention of muscle injuries is an ongoing process where intervention is necessary for as long as participants engage in the physical activities that place them at risk (Goldman and Jones, 2011). This process should be based on the four sequential steps of prevention model

**4.** evaluate the effectiveness of preventive measures introduced by repeating the analysis in

Many interventions are widely employed by participants, trainers, coaches and physiothera‐ pists specifically aiming to prevent muscle injuries. Among the most used interventions there are: exercises designed to improve muscle flexibility (Van Mechelen et al., 1993) and strength, in particular by means of eccentric exercises; exercises designed to improve balance, proprio‐ ception (Emery et al., 2007), neuromuscular control, and motor skills; education among "training and the risk of injury", functional training exercises and sport-specific activities

Despite the relatively high incidence of sport injuries, evidence of the efficacy of preventive interventions is not well established. In the Systematic Review of Cochrane collaboration Goldman and Jones (2011) assumed that there isn't evidence from randomised controlled trials to draw conclusions on the effectiveness of interventions used to prevent hamstring injuries in people participating in football or other high risk activities for these injuries. Manual therapy interventions aimed to prevention of muscle injuries have produced good results, but they

introduced by van Mechelen in the early 90s (Van Mechelen et al., 1992):

**2.** establish the etiology and mechanism of onset of sports injuries;

need to be confirmed with further research from RCTs of good quality.

**1.** determine the size of the problem sports injuries,

1999).

injuries is the predominant one.

**3.** insert the preventive measures;

step 1.

(Verrall et al., 2005).

Although much progress has been made in understanding the pathogenesis of muscle injuries, to date none of the proposed hypotheses can provide a unique explanation of their occurrence, and the multifactorial etiology is frequently evoked (Gleim and McHugh, 1997).

Depending on the trauma mechanism, muscle injuries can be classified as direct and indirect. The direct form is the *contusion*, and the indirect form is the *strain* (Järvinen and Lehto, 1993). A contusion occurs when a muscle is subject to a sudden and heavy compressive force, such as a direct blow provoked by an opposing player or by an object. Muscle strain usually arises from an indirect insult when an application of excessive tensile forces is produced.

The muscle-tendon junction (MTJ) is the most involved site in the acute muscle injuries (Garrett et al., 1988), and bi-articular muscle with a greater percentage of type II fibres and pennate architecture, as rectus femoris, hamstrings, adductor longus and gastrocnemius are the most commonly injured muscles (Hasselman et al., 1995; Hughes et al., 1995; Kasemkijwattana et al., 1998; Volpi et al., 2004).

Sprinting and jumping are the most common activities associated with muscle strains (Crisco et al., 1994).

Additionally, repeated eccentric muscle contractions can result in delayed-onset muscle soreness (DOMS) with symptoms similar to muscle injuries, including decreased function, stiffness, and pain (Warren et al., 2002). DOMS is attributable to a distinct pathophysiological process that includes an inflammatory response and structural changes of the sarcomere, with a consequent reduction of muscular functional ability (Barash et al., 2002; Lieber et al., 2002). In fact, mechanical damage and leukocyte infiltration after intense eccentric exercise are known to coincide with torque reductions (MacIntyre et al., 1996).

Although new classification systems of muscle injuries have been recently proposed (Mueller-Wohlfahrt et al., 2013; Chan et al., 2012), the most widely used system classifies muscle injuries (strain and contusion) according to their severity: amount of pain, weakness, loss of extensi‐ bility and reduction of ROM, functional impairment as in the walking or running (Kujala et al., 1997; Mason et al., 2007). A mild (grade I) injury involves damage to a small number of muscle fibers and localized pain without loss of strength. A clear loss of strength coupled with pain reproduced on resistance strength test is indicative of a moderate (grade II) injury. A severe (grade III) injury corresponds with complete rupture of the muscle and loss of strength and function (Verrall et al., 2003).

Generally, the risk factors for injury are divided into intrinsic (athlete related) and extrinsic (environment-related) (Inklaar, 1994; Taimela et al., 1990). Among the intrinsic factors most frequently identified by prospective studies are: age (Gabbe et al., 2006), fatigue (Greig and Siegler, 2009), a history of previous injury (Hagglund et al., 2006; Gabbe et al., 2010), postural and biomechanical deficits (Agre, 1985), lack of extensibility, and imbalance of agonist/ antagonist muscular strength and power ratio (Askling et al., 2003; Croisier et al., 2008).

Among the extrinsic factors, importance is attributed to inadequate warm-up, climatic factors, inadequate training, playground surface, inadequate sports equipment (Hawkins and Fuller, 1999).

Orchard and colleagues suggested that intrinsic factors are more predictive of a muscle injury than extrinsic factors. However, a recent systematic review concluded that no single risk factor (intrinsic or extrinsic) showed a significant correlation with hamstring muscles injuries (Foreman et al., 2006). For this reason, as mentioned above the multifactorial etiology of muscle injuries is the predominant one.

The prevention of muscle injuries is an ongoing process where intervention is necessary for as long as participants engage in the physical activities that place them at risk (Goldman and Jones, 2011). This process should be based on the four sequential steps of prevention model introduced by van Mechelen in the early 90s (Van Mechelen et al., 1992):


The management of muscle injuries, despite the lack of high quality studies, can be improved with the knowledge of the possible mechanisms that cause muscle injuries (Ekstrand et al., 1983), and with the identification of risk factors associated with injury occurrence (Verrall et al., 2003; Brockett et al., 2004). Acquisition of these knowledge will lead to an improvement of our preventive, therapeutic and rehabilitative strategies (Gibbs et al., 2004; Cross et al., 2004; Orchard and Best, 2002; Sherry and Best, 2004; Cacchio et al, 2006) for a safe return to sport

Although much progress has been made in understanding the pathogenesis of muscle injuries, to date none of the proposed hypotheses can provide a unique explanation of their occurrence,

Depending on the trauma mechanism, muscle injuries can be classified as direct and indirect. The direct form is the *contusion*, and the indirect form is the *strain* (Järvinen and Lehto, 1993). A contusion occurs when a muscle is subject to a sudden and heavy compressive force, such as a direct blow provoked by an opposing player or by an object. Muscle strain usually arises

The muscle-tendon junction (MTJ) is the most involved site in the acute muscle injuries (Garrett et al., 1988), and bi-articular muscle with a greater percentage of type II fibres and pennate architecture, as rectus femoris, hamstrings, adductor longus and gastrocnemius are the most commonly injured muscles (Hasselman et al., 1995; Hughes et al., 1995; Kasemkijwattana et

Sprinting and jumping are the most common activities associated with muscle strains (Crisco

Additionally, repeated eccentric muscle contractions can result in delayed-onset muscle soreness (DOMS) with symptoms similar to muscle injuries, including decreased function, stiffness, and pain (Warren et al., 2002). DOMS is attributable to a distinct pathophysiological process that includes an inflammatory response and structural changes of the sarcomere, with a consequent reduction of muscular functional ability (Barash et al., 2002; Lieber et al., 2002). In fact, mechanical damage and leukocyte infiltration after intense eccentric exercise are known

Although new classification systems of muscle injuries have been recently proposed (Mueller-Wohlfahrt et al., 2013; Chan et al., 2012), the most widely used system classifies muscle injuries (strain and contusion) according to their severity: amount of pain, weakness, loss of extensi‐ bility and reduction of ROM, functional impairment as in the walking or running (Kujala et al., 1997; Mason et al., 2007). A mild (grade I) injury involves damage to a small number of muscle fibers and localized pain without loss of strength. A clear loss of strength coupled with pain reproduced on resistance strength test is indicative of a moderate (grade II) injury. A severe (grade III) injury corresponds with complete rupture of the muscle and loss of strength

to coincide with torque reductions (MacIntyre et al., 1996).

and the multifactorial etiology is frequently evoked (Gleim and McHugh, 1997).

from an indirect insult when an application of excessive tensile forces is produced.

activities.

170 Muscle Injuries in Sport Medicine

al., 1998; Volpi et al., 2004).

and function (Verrall et al., 2003).

et al., 1994).

**4.** evaluate the effectiveness of preventive measures introduced by repeating the analysis in step 1.

Many interventions are widely employed by participants, trainers, coaches and physiothera‐ pists specifically aiming to prevent muscle injuries. Among the most used interventions there are: exercises designed to improve muscle flexibility (Van Mechelen et al., 1993) and strength, in particular by means of eccentric exercises; exercises designed to improve balance, proprio‐ ception (Emery et al., 2007), neuromuscular control, and motor skills; education among "training and the risk of injury", functional training exercises and sport-specific activities (Verrall et al., 2005).

Despite the relatively high incidence of sport injuries, evidence of the efficacy of preventive interventions is not well established. In the Systematic Review of Cochrane collaboration Goldman and Jones (2011) assumed that there isn't evidence from randomised controlled trials to draw conclusions on the effectiveness of interventions used to prevent hamstring injuries in people participating in football or other high risk activities for these injuries. Manual therapy interventions aimed to prevention of muscle injuries have produced good results, but they need to be confirmed with further research from RCTs of good quality.
