Compression garments and exercise: no influence of pressure applied.

Author:Beliard, Samuel
Position:Research article - Report
 
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Compression garments on the lower limbs are increasingly

popular among athletes who wish to improve performance,

reduce exercise-induced discomfort, and reduce the risk of

injury. However, the beneficial effects of compression garments

have not been clearly established. We performed a review of the

literature for prospective, randomized, controlled studies, using

quantified lower limb compression in order to (1) describe the

beneficial effects that have been identified with compression

garments, and in which conditions; and (2) investigate whether

there is a relation between the pressure applied and the reported

effects. The pressure delivered were measured either in laboratory

conditions on garments identical to those used in the studies,

or derived from publication data. Twenty three original articles

were selected for inclusion in this review. The effects of wearing

compression garments during exercise are controversial, as most

studies failed to demonstrate a beneficial effect on immediate or

performance recovery, or on delayed onset of muscle soreness.

There was a trend towards a beneficial effect of compression

garments worn during recovery, with performance recovery

found to be improved in the five studies in which this was investigated,

and delayed-onset muscle soreness was reportedly reduced

in three of these five studies. There is no apparent relation

between the effects of compression garments worn during or

after exercise and the pressures applied, since beneficial effects

were obtained with both low and high pressures. Wearing compression

garments during recovery from exercise seems to be

beneficial for performance recovery and delayed-onset muscle

soreness, but the factors explaining this efficacy remain to be

elucidated.

Key words: Compression garment, venous return, exercise,

muscle soreness, recovery, performance.

Introduction

Compression garments on the lower limbs are increasingly popular among athletes. Over a hundred types of compression stocking intended for use among athletes are currently commercially available. However, their beneficial effects have not been clearly demonstrated in the literature. As indicated by MacRae et al. (2011), there is great heterogeneity among experimental studies, in terms of the training status of the subjects, the type of exercise performed, the design of the compression garments tested (knee or thigh-high stockings, waist-down tights, arm sleeves, whole body garments), when they were worn (during and/or after exercise), and the level and spatial distribution of pressure applied. Indeed, in a number of studies, the pressure applied is not reported. It is possible that this heterogeneity between studies results in conflicting results that may mask the true efficacy of compression, which would only become apparent with more restrictive experimental conditions.

We aimed to investigate two questions through a review of the literature, namely: Firstly, what, if any, beneficial effects of compression have been demonstrated in the literature, and under which conditions of use. Among the factors influencing the potential efficacy of compression garments, the timing of their use (i.e. during exercise or/and during recovery) seems to be of major importance. Various mechanisms have been suggested to explain the beneficial effects reported in some studies. During exercise, a support effect has been assumed to reduce microtrauma and muscular damage (Trenell et al., 2006), reduce power expenditure (Bringard et al., 2006b), and improve comfort (Ali et al., 2007). During post-exercise recovery, hypotheses concerning the role of compression focus mainly on the classic effects of the compression, namely improvement of venous return and accelerated removal of metabolic waste (Hirai et al., 2002), limitation of edema (Partsch et al., 2012), increased arterial pulse blood flow (Mayrovitz et al., 2010), and increased oxygen delivery to the tissue (Bringard et al., 2006a). Although the exact mechanisms remain to be elucidated, they likely differ during exercise and during recovery, owing to the different physical conditions. Thus, in our analysis, we categorized studies into three groups, according to when the garment was worn. The type of exercise performed (endurance or resistance) was also taken into consideration.

Secondly, we sought to evaluate whether there is any relationship between the pressure applied and the reported effects. In the context of venous insufficiency, the effects of compression garments depend on the pressure applied, and the strength of compression recommended increases with the severity of disease. It could be assumed that a similar relation may also exist in the field of sports physiology. In practice, the choice of compression garment by athletes is mainly based on personal preferences, and not on the pressure delivered. If a relation were identified between the pressure applied and the benefit yielded, as in the case of venous disease, then this could help to better adapt the choice of garments to the expected effects.

Methods

Review of the literature

To identify original research addressing the effects of compression garments on sports performance and recovery after exercise, a computer-based literature search was performed in May 2014 using the electronic databases PubMed, MEDLINE, SPORT Discus, and Web of Science. Literature was searched over a 30-year period (up to and including May 2014). The key words used were: 'compression', 'compressive' 'garment', 'stocking', 'exercise', 'sport', 'performance', 'recovery', 'muscle soreness' and 'hemodynamic'.

Studies were eligible for inclusion in the analysis if they were prospective, with a clearly detailed protocol (type and duration of exercise, timing of garment's wear); included subjects were athletes of any level; the compression garment was applied on the lower body. The pressure garments used had to be described in detail (trademark, model, size) to allow precise identification and allow us to purchase it to evaluate the pressures really exerted. Only the in vitro (laboratory conditions) method of measure achieves reproducible measurement conditions, identical to those required for certifying the pressure levels of compression garments by the industry (French standards NFG30 102B). The in vivo measure is a local measure at a specific point, which is influenced by the radius of curvature of the limb at that particular point, and also by the tension of the textile. The in vitro measure is performed using a wooden structure with a circular (constant) radius of curvature. The pressure is indirectly measured on this wooden structure by using the Laplace law. The in vitro measure corresponds to the average pressure in vivo. The data analyses were therefore based either on pressure values indicated in the study (when performed in laboratory conditions), or on values measured in our laboratory with a compression garment identical to that tested in the relevant study (same trademark model, size). Retrospective studies and studies in which the compression garments were worn on the arm or on the whole body were excluded. Selected studies were categorized into three groups according to when the compression garment was worn: i.e. during exercise only, during recovery only, or during both exercise and recovery. The reference sections of all selected studies were manually searched for additional references not found by the initial online database search.

Measurement of the pressures delivered at ankle and calf levels according to the garment used

We were able to purchase one each of 12 garments out of the 24 studies analyzed. For each garment, we evaluated the pressures applied at the ankle and at the calf in laboratory conditions using a single method, which complies with the French standards (NFG30 102B) required for the reimbursement of medical compression garments by the social security system.

The measurements were performed as follows: The garment to be evaluated was placed on a 3D wooden leg template, the dimensions of which correspond to the size of the garment. The areas of interest (i.e. ankle and calf) were marked on the garment. The garment was removed from the template and left at rest for 2 hours to allow it to recover its initial state. Then the garment was placed on a dynamometer in the same strain conditions as those on the wooden leg template in order to measure the textile's tension under conditions of wear.

The pressure delivered (P) was calculated using Laplace's law: P = TxC, where T is the textile tension, and C the curvature of the template. All measurements were performed in the Biophysics Department of Innothera Laboratories (Arcueil, France).

The full text studies were read and selected by three of the co-authors. One hundred and fifty five original articles were identified, of which 24 fulfilled the criteria for inclusion and were analyzed in detail. Among the 24 articles selected, six reported several protocols, performed on the same subjects, but with different compression levels, yielding diverging results. In order to take this into account, we analyzed the results of each protocol individually. Thus, in this report, the overall number of studies may exceed the number of associated references.

The criteria of evaluation in the studies were classed in two categories, namely (1) variables that measured performance with and without compression, and (2) variables that report the quality of recovery with or without compression. The performance parameters estimated in the studies were: maximal oxygen consumption, energy cost, speed or power reached during the test, heart rate, cardiac output, muscular strength capacity, tissue oxygenation, perception of the difficulty of the exertion (Borg and other scales). The dosage of blood lactate concentration, and blood creatine kinase concentration were also evaluated to study the effects of wearing compression garment during a...

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