Page 102 - JSOM Fall 2018

land­based exercise found no difference in physical function­ off or actually decreased. Factors that increase OA risk include
ing scores. Pain was not evaluated in this review. 55 older age, black race, genetics, higher BMI, prior knee injury,
and excessive joint loading. Regular, moderate exercise assists
Tai chi is a form of aerobic exercise involving slow, deliberate, in maintaining normal cartilage and individuals performing
dance­like movements. It was developed in China as a form moderate levels of exercise show little evidence of OA. Once
of martial arts and has been shown to improve strength and OA develops, there is considerable evidence that many types of
balance. 80,81 Because this is a form of aerobic exercise, it is regular exercise (e.g., aerobic, resistance training) can reduce
not surprising that two reviews 56,58 have found that tai chi is pain and disability. In future articles, the effectiveness of other
effective in reducing the pain and disability associated with interventions for reducing the pain and disability of OA will
OA. A third review examined “Chinese exercises,” but most be addressed.
of these (seven of eight) were studies of tai chi. If all three
63
reviews 56,58,63 are included, the SMDs for the reduction in pain Disclaimer
(tai chi versus nonexercising control) ranged from 0.72 to The views expressed in this presentation are those of the au­
0.79; for improved physical functioning, SMDs ranged from thors and do not necessarily reflect the official policy of the
0.72 to 0.86. These SMDs are generally greater than those Department of Defense, Department of the Army, US Army
reported for other forms of exercise. Medical Department or the US government. The use of trade­
mark names do not imply endorsement by the US Army but is
Besides exercise modes, length and frequency of exercise pro­ intended only to assist in the identification of a specific product.
grams were examined in two reviews. 52,59 and results are pre­
sented in Table 2. Having fewer than 12 supervised sessions Author Contributions
was less effective in reducing pain and improving function JJK conceived the article, performed much of the research, and
than having at least 12 supervised sessions. Programs involv­ produced the first draft. RP, RO, and BS provided additional
59
ing three or more sessions per week more effectively reduced research and edited the article to produce the final draft. RP
pain and improved physical functioning than programs in­ also focused on accessibility by key readership groups. All au­
volving fewer than two sessions per week. thors approved the final version of the manuscript.

TABLE 2 Standardized Mean Differences (95% CI) From Reviews
That Examined the Effects of Length (Number of Sessions) and References
Frequency (Sessions/Week) of Physical Training Programs on Pain
and Physical Functioning in Osteoarthritis 1. Kraus VB, Blanco FL, Englund M, et al. Call for standarized defi­
nitions of osteoarthritis and risk stratification for clinical trials
Physical and clinical use. Osteoarthritis Cartilage. 2015;23:1233–1241.
Level Pain Functioning 2. Lawrence RC, Felson DT, Helmick CG, et al. Estimates of the
First Author of Variable SMD (95% CI) SMD (95% CI) prevalence of arthritis and other rheumatic conditions in the
Fransen 52 <12 sessions 0.28 (0.16, 0.40) 0.23 (0.09, 0.37) United States. Arthritis Rheumatol. 2008;58(1):26–35.
≥12 sessions 0.46 (0.32, 0.60) 0.45 (0.29, 0.62) 3. Park J, Mendy A, Vieira ER. Various types of arthritis in the
Juhl 59 <2 sessions 0.41 (0.25, 0.55) 0.33 (0.18, 0.49) united States: prevalence and age­related trends from 1999 to
2014. Am J Public Health. 2018;108(2):256–258.
≥3 sessions 0.68 (0.51, 0.85) 0.67 (0.44, 0.89) 4. Cross M, Smith E, Hoy D, et al. The global burden of hip and
Abbreviations: CI, confidence interval; SMD, standardized mean knee osteoarthritis: estimates from the Global Burden of Disease
difference. 2010 study. Ann Rheum Dis. 2014;73:1323–1330.
5. Felson DT, Lawrence RC, Hochberg MC, et al. Orthritis: new in­
One review examined exclusively resistance training studies sights. Part 2: treatment approaches. Ann Intern Med. 2000;133
62
and compared programs that followed the American College (9):726–737.
of Sports Medicine (ACSM) guidelines for strength training 6. Cameron KL, Hsiao MS, Owens BD, et al. Incidence of physician
with those that did not. The ACSM guidelines were considered diagnosed osteoarthritis among active duty United States service
members. Arthritis Rheumatol. 2011;63(10):2974–2982.
to be followed if the training load was greater than 40%, of a 7. Patzkowski JC, Rivera JC, Ficke JR, et al. The changing face of
one­repetition maximum, that 2 to 4 sets of 8 to 12 repetitions disability in the US Army: the Operation Enduring Freedom and
were performed to contraction failure or muscular exhaus­ Operation Iraqi Freedom effect. J Am Acad Orthop Surg. 2012;
tion, and the training frequency was at least 2 to 3 sessions per 20(Suppl 1):S23–S30.
week. It can be seen in Table 1, row 14, that although there 8. Williams VF, Clark LL, Oh GT. Update: osteoarthritis and
74
were larger SMDs for studies following the ACSM guidelines, spondylosis, active component, US Armed Forces, 2010–2015.
MSMR. 2016;23(9):14–22.
the authors found no statistically significant difference in the 9. Osteoarthritis and spondylosis, active component, US Armed
changes in pain or disability between the two types of studies. Forces, 2000­2009. MSMR. 2010;17(12):6–11.
However, knee­extensor strength gains were greater in studies 10. Fox AJ, Bedi A, Rodeo SA. The basic science of articular cartilage:
that followed the ACSM guidelines compared with those that structure. composition, and function. Sports Health. 2009;1(6):
did not (SMD, 0.83 [95% CI, 0.49, 1.17] versus 0.38 [95% 461–468.
CI, 0.27 0.50], p = .01). The authors estimated that a 30% and 11. Buckwalter JA. Athletics and osteoarthritis. Am J Sports Med.
1997;25(6):873–881.
40% increase in strength could have beneficial effects on pain 12. Hamerman D. The biology of osteoarthritis. New Engl, J Med.
and disability, respectively. 1998;320(20):1322–1330.
13. Chen C, Tambe DT, Deng L, et al. Biomechanical properties and
mechanobiology of the articular chondrocyte. Am J Physiol Cell
Summary Physiol. 2013;149:C1202–C1208.
OA involves deterioration of the articular cartilage and under­ 14. Sun HB. Mechanical loading, cartilage degradation, and arthritis.
Ann NY Acad Sci. 2010;1211:37–50.
lying bone with associated pain and disability. The incidence 15. Sinkov V, Cymet T. Osteoarthritis: understanding the pathophys­
of OA has been on the rise in the military since at least the year iology, genetics and treatments. J Natl Med Assoc. 2003;95(6):
2000, although recently (since 2012) it appears to have leveled 475–482.

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