IMMEDIATE EFFECTS OF CRYOTHERAPY ON STATIC AND DYNAMIC BALANCE

Abstract

Purpose/Background:

Cryotherapy is commonly used in physical therapy with many known benefits; however several investigations have reported decreased functional performance following therapeutic application thereof. The purpose of this study was to determine the effect of cryotherapy applied to the ankle on static and dynamic standing balance. It was hypothesized that balance would be decreased after cryotherapy application.

Methods:

Twenty individuals (aged 18 to 40 years) participated in this research project. Each participant was tested under two conditions: an experimental condition where subjects received ice water immersion of the foot and ankle for 15 minutes immediately before balance testing and a control condition completed at room temperature. A Biodex® Balance System was used to quantify balance using anterior/posterior (AP), medial/lateral (ML), and overall balance indices. Paired t‐tests were used to compare the balance indices for the two conditions with alpha set at 0.05 a priori. Effect size was also calculated to account for the multiple comparisons made.

Results:

The static balance indices did not display statistically significant differences between the post‐cryotherapy and the control conditions with low effect sizes. Dynamic ML indices significantly increased following the cryotherapy application compared to the control exhibiting a moderate effect size indicating decreased balance following cryotherapy application. No differences were noted between experimental and control conditions for the dynamic AP or overall balance indices while a small effect size was noted for both.

Conclusions:

The results suggest that cryotherapy to the ankle has a negative effect on the ML component of dynamic balance following ice water immersion.

Clinical Relevance:

Immediate return to play following cryotherapy application is cautioned given the decreased dynamic ML balance and potential for increased injury risk.

Level of Evidence:

3b Case‐control study

INTRODUCTION

Cryotherapy is commonly used during rehabilitation as a treatment modality for acute and chronic injuries.^1,2 The aims of cryotherapy interventions include pain reduction, inflammation control, and edema reduction.^1‐4 Despite the defined treatment benefits of cryotherapy, decreases in performance variables are likely if returning to activity immediately following cryotherapy treatments.⁵ Specifically, decreased muscle strength, vertical jump height, running speed, and agility measures have been noted following ice application across several anatomical areas and studies.^6‐10 Ice treatment has also been shown to increase deficits in postural sway among individuals who have had previous lateral ankle sprains.¹¹

Due to the mounting evidence that cryotherapy has deleterious immediate effects on functional activities, a further understanding of the possible impairments related to this commonly used treatment is warranted. Prior authors have reported decreased static standing balance following the effects of cryotherapy.^8,11 However, measures of dynamic standing balance may better represent the demands of the lower extremity during functional tasks and therefore may be a more appropriate assessment. Thus, the aim of this study was to assess the role of cryotherapy via foot and ankle ice water immersion on static and dynamic standing balance. It was hypothesized that balance would decrease in both the static and dynamic conditions following the cryotherapy application compared to the control condition. Findings from this study might assist clinicians in decision‐making regarding the use of cryotherapy within a treatment session or when considering return to play after an athletic injury.

METHODS

A single group repeated measures design was used under which each participant had their balance tested during two conditions: (1) an experimental condition where the subject received ice water immersion of the foot and ankle for 15 minutes immediately before balance testing and (2) a control condition completed at room temperature. The order of testing condition was randomized through a coin flip. Participants completing the control condition first immediately completed the experimental condition following assessment. Participants randomized to the cryotherapy condition first had the control session scheduled at a separate time to ensure no lingering effects existed from the cryotherapy procedures.

Participants

Twenty volunteer participants aged 18‐40 without foot or ankle injury in the preceding six months, known cold sensitivities (such as Raynaud's Disease), and known balance or proprioceptive deficits participated in the study. All participants provided informed consent prior to participation as per East Tennessee State University guidelines.

Cryotherapy Treatment

The foot and ankle of the dominant lower extremity was immersed in an ice water filled basin to a level at least five centimeters above the medial malleolus for fifteen minutes.¹² The temperature of the water was monitored and adjusted (with additional ice) as needed to ensure the temperature remained below 4.4°C.

Balance Testing

The Biodex^® Balance System (BBS) was used to measure balance during static and dynamic conditions. During static conditions the BBS circular platform acts as a standard force plate thus allowing for static balance testing. Static results are reported as the angular displacement of the center of gravity as defined by the manufacturer. Dynamic balance testing was performed on the same platform that was unlocked to allow free movement simultaneously in both the medial/lateral (ML) and anterior/posterior (AP) directions. The platform allows varying levels of resistance to perturbation of movement ranging from 1 to 8 (8 being least restrictive) as set by the manufacturer. Rather than measuring the deviation of the center of gravity as done during static conditions, this device measures the degree of tilt about each axis during dynamic measurements.¹³ Utilizing this data, the BBS software quantifies balance indices for AP and ML stability, and overall stability (OA) based on tilt variance, whereby a large variance indicates reduced balance.¹³ Reliability of the BBS using this protocol has been previously calculated as r=.89 for AP, r=.93 for ML, and r=.92 for OA.¹⁴ Each participant completed a practice session for static and dynamic testing immediately prior to balance measurement.¹⁵ Static balance testing preceded dynamic balance testing for all individuals. Following familiarization, three ten second trials, each separated by a 20 second rest period, were used to calculate the balance indices for each participant. The average of the three measures was used for analysis. Dynamic balance was measured using the same protocol as static balance testing with the BBS set to a dynamic position of 4 out of 8. This level was chosen as it was in the middle of the available levels of platform restrictiveness. Testing was performed barefoot on the dominant lower extremity as determined by the Otago Footedness Inventory.¹⁶ All balance tests were completed with the participants' hands on their hips and with eyes open. No visual feedback regarding the location of the center of gravity or tilt from the BBS computer screen was provided (Figure 1). Any trials in which the participants' hands moved from their hips or the non‐tested lower extremity touched down were deleted and repeated. Less than 20% of participants were required to repeat trials due to loss of balance.

Figure 1.

Participant Testing Position on the Biodex^® Balance System.

Statistical Analyses

Paired t‐tests were used to compare balance scores between the post ice water immersion and the control condition. Alpha was set at 0.05 a priori. Effect size (ES) was computed utilizing the effect size index (mean balance difference /control standard deviation) to assist in determination of meaningfulness of change scores due to multiple comparisons.^17,18 Effect sizes ranging from 0.20‐0.49 indicate small change, 0.50‐0.79 indicate moderate change, and ≥ 0.80 indicate large change.¹⁹

RESULTS

Participants' demographics were 23.9 ± 2.0 years old, 170.7 ± 11.5 cm, and 69.7 ± 10.3 kilograms (Table 1). Nineteen participants were right foot dominant while one was left foot dominant.

Table 1.

Participant Demographic Information

Age	23.9 ± 2.0 years
Height	170.7 ± 11.5 cm
Mass	69.7 ± 10.3 kg

All values are mean ± standard deviation

No balance differences and small effect sizes were noted during the static condition for the AP (p=0.992, ES<0.01), ML (p=0.611, ES=0.03) or OA (p=0.919, ES=0.07) (Figure 2). The dynamic condition yielded significantly increased tilt and a moderate effect size for the ML direction only (p= 0.026, ES=0.78). Tilt variation did not differ in the AP direction (p=0.236, ES=0.34) or OA (p=0.142, ES=0.43) (Figure 3) with small effect sizes noted.

Figure 2.

Static Balance Testing Results with the Component and Overall Measures.

Figure 3.

Dynamic Balance Testing Results with the Component and Overall Measures.

DISCUSSION

This study found decreased ML dynamic standing balance (as noted by increased ML tilt variance and moderate effect size) among this group of participants without ankle or lower extremity injury following cryotherapy application. To the authors knowledge this study was the first to assess the role of immersion cryotherapy on dynamic standing balance in a group of uninjured individuals. Prior investigations have assessed the role of cryotherapy solely on static standing balance.¹¹ The dynamic measurement utilized in the current study may better approximate functional activities due the increased demand of lower extremity to maintain standing balance as is required with the majority of functional tasks. Further, alterations in dynamic (versus static) balance may better explain some of the functional decreases in vertical jump height, running speed and agility that have been previously reported.^6‐10 The authors of a recent systematic review have indicated that cryotherapy has no definitive negative influence on proprioception across several joints.²⁰ While some authors report decreased proprioceptive acuity following cryotherapy, others results are equivocal.^21‐26 Similar to static balance testing, most proprioceptive measures have been performed during experimental conditions that occur in controlled motions or at very slow speeds and do not adequately represent function. Prior studies assessing functional performance following cryotherapy have postulated that decreased balance likely contributed to the adversely affected function yet this was not measured.⁸ Other proposed mechanisms leading to decreased performance not encompassed in this study include: increased joint stiffness, decreased muscle, tendon, and ligament elasticity, altered plantar surface afferent information, or an altered neurophysiological and neuromuscular response.^20,27 As this was not a mechanistic study, any one or more of these potential mechanisms may be responsible for the increased ML tilt variance noted in the current study or functional deficits noted in prior studies.

Lateral ankle sprains account for over 85% of all ankle sprain injuries with the anterior talofibular ligament most commonly involved.^28,29 Lateral ankle sprains most commonly occur with an inversion mechanism of injury affecting stability of the ankle in the frontal plane.²⁸ The combined effects of lateral ankle sprain and cryotherapy on static standing balance has been recently reported.¹¹ Altered medial/lateral static standing balance was noted among ankle injured participants compared to the uninvolved leg and the balance alteration was augmented following cryotherapy application.¹¹ Dynamic standing balance was not assessed in this prior study. Given the findings of the current study, it may be inferred that ML dynamic balance would be decreased to a greater extent than during the static condition and might further injure the involved ankle or increase additional injury risk if attempting to perform dynamic functional tasks.^30,31 Additionally, peroneal muscle activation has been shown to be decreased in individuals post lateral ankle sprain.³² Given the peroneal muscles' role in medial/lateral ankle stability and the decreased dynamic balance found in this study, immediate return to activities following lateral ankle sprain and cryotherapy appears unjustified. The increase in ML tilt variance noted among this group of uninjured participants is concerning given the common application of cryotherapy following lateral ankle sprain with intention for return to play or practice in sporting events. Clinicians should use caution with the intention of returning an athlete to play following cryotherapy. The role of dynamic (versus static) balance should be assessed prior to return to play given the demonstrated responsiveness and larger effects sizes of the dynamic assessment found in this study.

Clinically, the order and timing of cryotherapy administration should be considered. Intervention schemes aimed at rehabilitation for lateral ankle sprain often target pain management, range of motion, strength, balance, and return to functional activities.³³ Balance retraining may be appropriate prior to cryotherapy application to limit the balance alterations that occur during dynamic functional activities immediately post cryotherapy. In a clinical setting, ice immersion may not necessarily be contraindicated prior to submaximal strengthening or rehabilitative exercise when done in a controlled environment under clinician supervision.³⁴ These submaximal controlled activities are likely best simulated by the static condition tested in this study, which was not adversely affected by the ice treatment. Immersion cryotherapy to the foot and ankle immediately before returning an athlete to unconstrained functional and sporting tasks whether in the clinic or on the field is cautioned given the deleterious effects noted on dynamic ML balance found in this study.

As with all studies, some limitations must be noted. This research was performed on individuals without ankle or foot injury. The role of dynamic standing balance should be explored in patients with ankle injuries and may differ from the findings of this study. This study assessed only the acute effects of cryotherapy on balance. The length of time dynamic balance is impaired remains to be determined and has great potential implications for clinical and on the field care. Additionally, the clinical meaningfulness or impact of increased tilt variance during dynamic balance testing is unknown. However, the moderate effect size noted (0.78) for ML balance indicates impactful changes did occur following cryotherapy treatment. Finally, this study assessed only the role of immersion cryotherapy on balance, others modes of cryotherapy treatment may yield differing results.²⁰

CONCLUSION

The results of the current study suggest that fifteen minutes of foot and ankle ice water immersion impairs dynamic ML standing balance. Sports medicine professionals utilizing cryotherapy as part of clinical rehabilitation techniques or with the intention of returning an athlete to play or practice should consider the implication of decreased dynamic balance on these activities.