By: ATH Director of Human Performance Frank Bourgeois, PhD
As people become more active to improve general health and athletic performance there is an innate increase in the likelihood of sustaining an injury. A key element, regardless of injury stage, that aides in injury risk reduction and reduced recovery time after injury is the ability to generate force, or strength.
In this article, we discuss the favorable physiological and biomechanical adaptations that are associated with a planned, informed, methodical approach for reconditioning not only the affected body part, but for the entire body in three distinct categories: preventative and pre-operation, post-operation and acute treatment, and return to participation/competition.
Activities of daily life impose seemingly endless task, environmental and individual constraints on the human body [4,12,21,24,39]. An integral element in solving these motor problems is the ability to generate force. Force generation capacity, or strength, is widely accepted as foundational for injury risk reduction and performance enhancement [33,53,51,52]. Equally, the health and performance benefits of exposure to supervised evidence-led strength training are well documented [25,32,33,43,56]. The key principle underpinning the efficacy of this training mode is progressive mechanical overload [16,55]. That is – to gradually increase the application of an external load (i.e. force) on biological tissue. This mechanical overload has been shown to signal the advantageous remodeling of passive and active structures responsible for movement [1,10,55].
Increasingly, medical and performance practitioners are being challenged to address the immediate and long-term movement needs of an array of individuals that range from three days post-operation to high-performing athletic status. As such, there is research supporting the application of evidence-led strength training across this broad spectrum of psycho-physical conditions [11,17,20,23,25,41,43]. The aim of this report is to provide empirical data that highlight the importance of employing strength training to improve neuromotor capabilities in three identified categories: 1) preventative and pre-operative, 2) post-operative and acute treatment, and 3) return to participation and return to competition.
Preventative and pre-operation categories are defined as the periods of time when an individual is able to conduct normal activity (i.e. healthy status), and when an individual has a scheduled surgical intervention, respectively. Post-operation is defined as 1 to 3 days after surgical intervention, while acute treatment is defined as 4 to 14 days. Finally, return to participation and return to competition share the concept of criteria-based progression to globally reconditioning the body. However, they are distinguished by outcome specificity. The reconditioning of return to participation intervention is for resuming normal activity, while that of return to competition is for sport-specific high-performance.
Preventative and pre-operation
There is overwhelming extant data that demonstrate the positive influence strength training has on individuals categorized as preventative [32,34] and pre-operation [14,23,25,45]. Prophylactic effects associated with strength training include increased resiliency and function of cardiac [3,26] and skeletal muscle [1,14,18,25,26,36,40,55], connective tissue , nervous tissue [2,4,6,15,19,44], cardiopulmonary tissue [3,26] and metabolic processes [3,22,26,27]. The enhanced architecture and function within the neuromotor system is a result of consistent exposure to systemic mechanical overload [1,2,5,7,16,44,55]. That is, repetitively challenging the body to coordinatively operate beyond ‘resting state’.
These advantageous tissue modifications are largely realized via increased mechanical stress and strain tolerance due to increased muscle-tendon unit (MTU) length and increased force capabilities [33,55]. These protective qualities are associated with the enhancement of performance qualities. For instance, an increase in MTU length increases muscle fiber shortening velocity (i.e. speed of contraction), while an increase in force-generating capabilities will increase mechanical output in pushing and pulling tasks . In the rehabilitation context, the benefit of enhancing biological features (e.g. a change in myosin isoform expression and increased collagen synthesis), and thus mechanical function (e.g. increased triaxial force production) prior to surgical intervention has been documented [14,22,23,25], with retention lasting 12 weeks post-operation . Interestingly, in addition to heightened neuromuscular function following a 6-week pre-operative rehabilitation program compared to a control group, Hägglund and colleagues (2015) noted the increased efficacy of executing a rehabilitation program at a “specialized” facility, providing value to the centralization of supervised patient/athlete care .
Post-operation and acute treatment
The post-operative benefits of a reconditioning program with a concomitant focus on enhancing the strength capabilities and range-of-motion of coordinative structures have received enormous attention in sports medicine literature . However, with the obvious advantage of strength training on the reconditioning process, attention has diverted to testing the efficacy of an accelerated reconditioning program – that is, a strength program aimed to encourage restoration of strength early (e.g. <10 months post-op) [46,47,49]. Though an area of controversy due to potentially heightened injury risk and other limitations [46,50,48], there is evidence of accelerated reconditioning being superior to that of a traditional program [47,48]. Shelbourne and Gray (1997) demonstrated favorable radiographs, acceptable range-of-motion and joint laxity, and muscle strength in a longitudinal study . Importantly, individuals returned to normal activities on average in 3.1 weeks (range = 0.7 to 20, SD = 2.1), sport-specific activities reinstated at 6.2 weeks (range = 1 to 13, SD = 2.3) with full participation in competition occurring at 6.2 months (range = 2 to 18, SD = 2.3).
Return to participation and competition
It has been suggested that the emphasis of reconditioning interventions in this category, particularly in the latter days, should focus on load application that facilitates full restoration of coordinative structures associated with the involved area (e.g. reestablishing performance of the kinetic chain within the hip-knee-ankle complexes in locomotive tasks following unilateral knee injury) [13,21,24,29,55]. Additionally, and potentially more important, more attention is given to enhancing the global (i.e. whole-body) performance of an individual that desires to either return to normal activities or return to competitive environments .
Though end-goals may differ, each of these individuals necessitates a service that warrants a collaborative approach primarily between sports medicine and sports performance practitioners [9,30]. Such an interdisciplinary approach would substantially increase the likelihood of short- and long-term success via accurate identification for entry into respective programs [8,29,37], valid and reliable metrics to track function/performance [42,54] and appropriate systematic strength training [28,51].
Athlete Training + Health would like to thank Shelbie Miller of Texas Health Sports Medicine at Arlington for her assistance in the development of this manuscript. Thank You.
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