Unstable surface training as a rehabilitation exercise modality improves strength, range of motion, and postural control in young adults with grade 1 ankle sprain

Background: Ankle sprains are one of the most common musculoskeletal injuries in young adults, often leading to chronic ankle instability if inadequately rehabilitated. Restoring range of motion (ROM), strength, and postural balance are critical to prevent recurrence. This study investigated the comparative effects of stable surface training (SST) and unstable surface training (UST) on ankle joint function and balance in individuals with Grade 1 ankle sprains. Methods: Twenty healthy adult males diagnosed with Grade 1 ankle sprains were randomly assigned to SST (n = 10) or UST (n = 10) groups. Participants underwent a 4-week balance training program, three times per week. Pre- and post-intervention assessments included ankle joint ROM (dorsiflexion, plantarflexion, inversion, eversion), isokinetic muscle function, and static and dynamic balance tests (eyes-closed single-leg stance test (ECSLT) and Y-balance test). Results: Both groups showed significant improvements over time in ankle strength and balance (p < 0.05). However, only the UST demonstrated significant increases in dorsiflexion, plantarflexion, and inversion ROM (p < 0.05), as well as in total and average ROM (p < 0.05). While both SST and UST enhanced balance, UST showed a greater tendency for improvement, particularly in dynamic postural control. UST was more effective than SST in improving multidirectional ankle ROM and enhancing postural balance. Conclusions: These findings suggest that proprioceptively challenging rehabilitation protocols should be prioritized in early-stage rehabilitation for Grade 1 ankle sprains to support comprehensive functional recovery. Clinical Trial Registration: This study was registered in the Clinical Research Information Service (CRiS), Republic of Korea, under the registration number KCT0010569 (https://cris.nih.go.kr/cris/search/detailSearch.do?seq=30039&search_page=L).

Ankle sprain; Rehabilitation exercise; Proprioception; Functional recovery; Balance training

[1] Willems TM, Witvrouw E, Delbaere K, Mahieu N, De Bourdeaudhuij L, De Clercq D. Intrinsic risk factors for inversion ankle sprains in male subjects: a prospective study. The American Journal of Sports Medicine. 2005; 33: 415–423.

[2] Doherty C, Delahunt E, Caulfield B, Hertel J, Ryan J, Bleakley C. The incidence and prevalence of ankle sprain injury: a systematic review and meta-analysis of prospective epidemiological studies. Sports Medicine. 2014; 44: 123–140.

[3] Delahunt E, Bleakley CM, Bossard DS, Caulfield BM, Docherty CL, Doherty C, et al. Clinical assessment of acute lateral ankle sprain injuries (ROAST): 2019 consensus statement and recommendations of the International Ankle Consortium. British Journal of Sports Medicine. 2018; 52: 1304–1310.

[4] Hertel J. Functional instability following lateral ankle sprain. Sports Medicine. 2000; 29: 361–371.

[5] McKeon PO, Hertel J. Systematic review of postural control and lateral ankle instability, part I: can deficits be detected with instrumented testing? Journal of Athletic Training. 2008; 43: 293–304.

[6] Fong DT, Hong Y, Chan L, Yung PS, Chan K. A systematic review on ankle injury and ankle sprain in sports. Sports Medicine. 2007; 37: 73–94.

[7] Lin CC, Hiller CE, de Bie RA. Evidence-based treatment for ankle injuries: a clinical perspective. Journal of Manual & Manipulative Therapy. 2010; 18: 22–28.

[8] Vuurberg G, Hoorntje A, Wink LM, van der Doelen BFW, van den Bekerom MP, Dekker R, et al. Diagnosis, treatment and prevention of ankle sprains: update of an evidence-based clinical guideline. British Journal of Sports Medicine. 2018; 52: 956.

[9] Han J, Anson J, Waddington G, Adams R, Liu Y. The role of ankle proprioception for balance control in relation to sports performance and injury. BioMed Research International. 2015; 2015: 842804.

[10] Eils E, Rosenbaum D. A multi-station proprioceptive exercise program in patients with ankle instability. Medicine & Science in Sports & Exercise. 2001; 33: 1991–1998.

[11] Kaminski TW, Hertel J, Amendola N, Docherty CL, Dolan MG, Hopkins JT, et al. National athletic trainers’ association position statement: conservative management and prevention of ankle sprains in athletes. Journal of Athletic Training. 2013; 48: 528–545.

[12] Bleakley CM, O’Connor SR, Tully MA, Rocke LG, MacAuley DC, Bradbury I, et al. Effect of accelerated rehabilitation on function after ankle sprain: randomised controlled trial. The BMJ. 2010; 340: c1964.

[13] Docherty CL, Valovich McLeod TC, Shultz SJ. Postural control deficits in participants with functional ankle instability as measured by the balance error scoring system. Clinical Journal of Sport Medicine. 2006; 16: 203–208.

[14] Bleakley CM, Taylor JB, Dischiavi SL, Doherty C, Delahunt E. Rehabilitation exercises reduce reinjury post ankle sprain, but the content and parameters of an optimal exercise program have yet to be established: a systematic review and meta-analysis. Archives of Physical Medicine and Rehabilitation. 2019; 100: 1367–1375.

[15] Gioftsidou A, Malliou P, Pafis G, Beneka A, Tsapralis K, Sofokleous P, et al. Balance training programs for soccer injuries prevention. Journal of Human Sport and Exercise. 2012; 7: 639–647.

[16] Hrysomallis C. Balance ability and athletic performance. Sports Medicine. 2011; 41: 221–232.

[17] Hrysomallis C. Relationship between balance ability, training and sports injury risk. Sports Medicine. 2007; 37: 547–556.

[18] Anderson KG, Behm DG. Maintenance of EMG activity and loss of force output with instability. The Journal of Strength and Conditioning Research. 2004; 18: 637–640.

[19] Nam H, Cha H, Kim M. The effects of exercising on an unstable surface on the gait and balance ability of normal adults. Journal of Physical Therapy Science. 2016; 28: 2102–2104.

[20] McKeon PO, Ingersoll CD, Kerrigan DC, Saliba E, Bennett BC, Hertel J. Balance training improves function and postural control in those with chronic ankle instability. Medicine & Science in Sports & Exercise. 2008; 40: 1810–1819.

[21] Munn J, Beard DJ, Refshauge KM, Lee RY. Eccentric muscle strength in functional ankle instability. Medicine & Science in Sports & Exercise. 2003; 35: 245–250.

[22] Springer BA, Marin R, Cyhan T, Roberts H, Gill NW. Normative values for the unipedal stance test with eyes open and closed. Journal of Geriatric Physical Therapy. 2007; 30: 8–15.

[23] Gribble PA, Hertel J. Effect of lower extremity muscle fatigue on postural control. Medicine & Science in Sports & Exercise. 2002; 34: S39.

[24] Choi JH. Effects of elastic band exercise using proprioceptive neuromuscular facilitation on strength and dynamic balance of adults with ankle instability. Medico-Legal Update. 2019; 19: 628–634.

[25] Youdas JW, Bogard CL, Suman VJ. Reliability of goniometric measurements and visual estimates of ankle joint active range of motion obtained in a clinical setting. Archives of Physical Medicine and Rehabilitation. 1993; 74: 1113–1118.

[26] Valovich-mcLeod TC, Shultz SJ, Gansneder BM, Perrin DH, Drouin JM. Reliability and validity of the Biodex system 3 pro isokinetic dynamometer velocity, torque and position measurements. European Journal of Applied Physiology. 2004; 91: 22–29.

[27] Hoch MC, McKeon PO. Peroneal reaction time after ankle sprain. Medicine & Science in Sports & Exercise. 2014; 46: 546–556.

[28] Emery CA. Effectiveness of a home-based balance-training program in reducing sports-related injuries among healthy adolescents: a cluster randomized controlled trial. Canadian Medical Association Journal. 2005; 172: 749–754.

[29] Zhang C, Luo Z, Wu D, Fei J, Xie T, Su M. Effectiveness of exercise therapy on chronic ankle instability: a meta-analysis. Scientific Reports. 2025; 15: 11709.

[30] Taube W, Gruber M, Gollhofer A. Spinal and supraspinal adaptations associated with balance training and their functional relevance. Acta Physiologica. 2008; 193: 101–116.

[31] Hortobágyi T, Maffiuletti NA. Neural adaptations to electrical stimulation strength training. European Journal of Applied Physiology. 2011; 111: 2439–2449.

[32] Kleim JA, Jones TA. Principles of experience-dependent neural plasticity: implications for rehabilitation after brain damage. Journal of Speech, Language, and Hearing Research. 2008; 51: S225–S239.

[33] Delahunt E, Monaghan K, Caulfield B. Altered neuromuscular control and ankle joint kinematics during walking in subjects with functional instability of the ankle joint. The American Journal of Sports Medicine. 2006; 34: 1970–1976.

[34] Wikstrom EA, Tillman MD, Chmielewski TL, Cauraugh JH, Naugle KE, Borsa PA. Dynamic postural control but not mechanical stability differs among those with and without chronic ankle instability. Scandinavian Journal of Medicine & Science in Sports. 2010; 20: e137–e144.

[35] Hung Y. Neuromuscular control and rehabilitation of the unstable ankle. World Journal of Orthopedics. 2015; 6: 434–438.

[36] Herzog MM, Kerr ZY, Marshall SW, Wikstrom EA. Epidemiology of ankle sprains and chronic ankle instability. Journal of Athletic Training. 2019; 54: 603–610.

[37] Liu Z, Yamaguchi R, Fu S, Zhao H, Li Y, Kobayashi Y, et al. Epidemiology of ankle sprain and chronic ankle instability in elite adolescent dancesport athletes. The Physician and Sportsmedicine. 2025; 53: 119–128.

[38] Arnold BL, De La Motte S, Linens S, Ross SE. Ankle instability is associated with balance impairments. Medicine & Science in Sports & Exercise. 2009; 41: 1048–1062.

[39] Gribble PA, Hertel J, Plisky P. Using the star excursion balance test to assess dynamic postural-control deficits and outcomes in lower extremity injury: a literature and systematic review. Journal of Athletic Training. 2012; 47: 339–357.

[40] Gribble PA, Hertel J. Effect of hip and ankle muscle fatigue on unipedal postural control. Journal of Electromyography and Kinesiology. 2004; 14: 641–646.

[41] Ha S, Han J, Sung Y. Effects of ankle strengthening exercise program on an unstable supporting surface on proprioception and balance in adults with functional ankle instability. Journal of Exercise Rehabilitation. 2018; 14: 301–305.

[42] Myer GD, Ford KR, Palumbo JP, Hewett TE. Neuromuscular training improves performance and lower-extremity biomechanics in female athletes. The Journal of Strength and Conditioning Research. 2005; 19: 51–60.

[43] Liu X, He M, Hu R, Chen Z. Randomized controlled trial study of intelligent rehabilitation training system for functional ankle instability. Scientific Reports. 2024; 14: 4996.

[44] Docherty CL, Gansneder BM, Arnold BL, Hurwitz SR. Development and reliability of the ankle instability instrument. Journal of Athletic Training. 2006; 41: 154–158.