Early active mobilization has been recommended since 1953 according to Woodard, and should start as soon as spontaneous motion is painless [20, 21]. It must be progressive with validation step by step. From a more analytical point of view, eccentric exercises should be started as soon as walking is painless, to allow the muscle to contract as well as to stretch. The myofibers and their conjunctive envelopes should heal according to lines of force connected to these drives. These exercises are usually progressive, carried out according to internal, and then average and external muscle course, that is with a muscle length always higher. It is recommended that these exercises begin slowly, at 10° per second for example, increasing to 30° per second with submaximal muscle recruitment to remain pain free. This type of rehabilitation is more or less easy to perform according to the site of the muscle injury. To control the joint movement, eccentric exercises could be started manually or with an isokinetic dynamometer [17] (Fig. 8.2). However, compensation by the muscle heads is possible in cases of poly-joint muscle injury such as injury to the hamstring. For example, the biceps femoris is easily recruited during knee flexion and can compensate for the injured internal rotator muscles of the other knee.

The hamstring muscles have been studied in particular because the muscle is frequently injured. The four solid methodological studies mentioned previously allow some certainty with regard to stretching, trunk stabilization, eccentric exercises associated with running and the lack of efficacy of the sacroiliac manipulations [26].

Stretching four times a day for 30 s is more effective than stretching only once a day. A study of two groups of 40 randomized injured subjects, found that those who stretched four times a day returned to play 1.8 days earlier, on average, than those who stretched once a day [25].

Agility and trunk stabilization using isometric trunk training and one-limb balance exercises allows better results in terms of protection against re-injury and rapid return to sport activity (22 days ± 8 against 37 days ± 25) compared with stretching and strengthening of the injured hamstring muscle [34]. However, that study included only 12 subjects. More recently, this type of exercise was blind compared with eccentric strengthening associated with running in 51 randomized patients. No difference was found between the two types of rehabilitation in terms of return to play which averaged between 25 and 28 days [36]. At return to play, there were still signs of trauma visible on MRI, even though most of the patients were clinically pain-free. Four subjects were reinjured during the 12 month follow-up, with two of them at the very end of their rehabilitation period.

Passive stretching with sacroiliac manipulation is not effective [7]. However, the results makes sense when the two groups, treated and control, are compared before treatment. In fact, a meta-analysis on this subject by Mason et al. summarizes very well the misunderstanding of treatment of muscle injuries [26]. Only some parameters are studied: range of motion of the joint, muscle strength or re-injury. There is no single definition of time to return to play, despite harmonization plans proposed by various sports federations. Certain interesting parameters have been little studied: pain, muscular atrophy, or patient satisfaction. The number and the duration of treatments remain empirical while the effect of simple rest has never been studied.

Therapeutic ultrasound produces vibrations and heat, which aggravate the injury during the acute phase, and thus it is used only at the end of the treatment to decrease pain and tenderness while the collagen tissues heal. The efficacy of treatment has not been validated in humans or animals [32].

Electrical muscle stimulation is the application of an electrical current to the skin to provoke a muscle contraction. The myofibers are recruited, however, contrary to the physiological process. The fibers contract directly and locally under electrodes according to the quantity of current delivered, with no possibility of voluntary control of the contractions. Temporal and spatial recruitment are not respected, and there is some risk of worsening the injury during its acute phase.

Massage is mechanical palpation of the skin to exert varying pressure on the muscle according to the spatial orientation of the muscle. This treatment can aggravate the injury during the acute phase by manipulating the site of pain. Any link with between massage and muscular calcification, however, has not been proved [2].

Nonsteroidal anti-inflammatory drugs (NSAIDs) are sometimes proposed for temporary relief during the acute phase to limit the inflammatory cell reaction. No adverse effects on the healing process or on tensile strength have been shown. However, NSAIDs should not be used during the first 3–5 days after injury because they delay the phagocytosis phase of necrosis. On the other hand, the long-term cures showed negative effects on muscle regeneration [28].

Corticoids must not be used because they decrease muscle regeneration and prolong the healing process [2]. Intramuscular corticosteroid injection decreases pain but the association with an anesthetic drug masks any analgesic role they may play. There is no proof that they shorten the duration of healing in the absence of any controlled studies and despite a retrospective study of 431 (American) football players [24].

This technique was developed from animal experiments with the aim of favoring soft tissue healing by providing additional oxygen. The treatment places the injured subject in a compression chamber with 100 % oxygen 45 min twice a day for 5 days. In humans, this process has been used in several therapeutic indications: ankle and medial collateral knee sprain or prevention of delayed onset muscle soreness after eccentric exercise. At present, the utility of hyperbaric oxygen therapy for treating muscle injuries has not been studied. Nevertheless, this treatment has already been proposed for treating injuries in professional soccer players for example. The limits of this treatment are its cost and limited accessibility.

Several animal studies on tissue regeneration have reported interesting results when they injected autologous conditioned serum at the level of the muscle injury. Injured subjects who were treated with autologous serum returned to play 6 days sooner, on average, than those who were treated with Traumeel®: 16 days versus 22 days [37]. Traumeel® was then considered as a homeopathic mixture taken as placebo. Numerous study biases were present. The two groups were of different size, 18 in the group treated by autologous serum and 11 in the Traumeel® group. Muscle injuries were not homogenous with an abdominal muscle injury in the treated group that was cured in 8 days, which significantly improved the results.