The increasing prevalence of type 2 diabetes is a major health concern. Reducing the vascular complications of diabetes has been a primary focus of treatment. However, the less-recognized complications of physical disability, cognitive impairment, and depression that impact on quality of life (QOL) are also important primary care considerations in older patients with diabetes.

Diabetes has been associated with a greater risk of decline in function and increased prospect of severe disability (1,2). Studies have sought to identify relationships or causal pathways between the syndromes of mobility, disability, and neuropsychological function in adults with type 2 diabetes (1,3). Few have simultaneously examined these factors potentially modifiable by physical activity (4) across multiple domains or at more than one point in time.

The dose of aerobic and resistance exercise necessary to achieve metabolic benefits in clinical trials has sometimes led to poor compliance (5). Older adults with diabetes, often characterized by long-term sedentariness, overweight/obesity, and multiple comorbidities, may demonstrate better adherence to a low-intensity, low-impact exercise, such as Tai Chi. Although Tai Chi has demonstrated improved balance, gait speed, muscle strength, cardiorespiratory fitness, and QOL in older adults (613), it has never been tested specifically in a diabetic cohort for benefits across multiple domains.

If Tai Chi was shown to be effective for mobility and other health outcomes relevant to this cohort, it may present a viable alternative exercise modality. The aim of this study was to examine the physiologic impairments associated with mobility in older adults with type 2 diabetes and to investigate whether Tai Chi would improve mobility in this cohort relative to sham exercise.

We conducted a 16-week single-blind, randomized, sham-exercise controlled trial with an intention-to-treat design. Baseline outcomes assessment was blinded. The study was approved by human research ethics committees of the Universities of Sydney and New South Wales. Written informed consent was obtained by participants.

We studied 38 type 2 diabetic patients (79% female). We excluded patients who were physically active, institutionalized, or cognitively impaired (Mini-Mental State Examination ≤24) (14) or had arthritic pain, unstable conditions, or disease precluding them from the planned exercises. Participants were randomly allocated to the Tai Chi or control groups, named Eastern or Western exercise, both presented as being potentially beneficial. The same exercise physiologist conducted both group exercise sessions (10 min warm-up and cool-down, 45 min exercise) twice weekly. The Tai Chi group performed Tai Chi for Diabetes (15), a 12-movement hybrid from Sun and Yang styles. Control subjects performed sham exercise (e.g., seated calisthenics, stretching) (16).

All testing was conducted by the exercise physiologist before randomization and after completing 32 sessions (within 5 months of randomization). Mobility impairment was determined from measures of balance and gait speed (habitual and maximal). Static balance (timed single-leg stance with eyes open and closed), dynamic balance (3-m forward tandem walk), and balance index (summary score of static balance and postural control performance on a Chattecx balance platform) (17) were measured.

Physiological capacity assessments included knee extensor strength (one repetition maximum), peak power, peak contraction velocity, and endurance (18) and overall exercise capacity (6-min walk) (19). Health status included number of comorbidities, body composition (waist circumference, total body fat [%BF]) (20), fasting blood glucose, cognition (14), QOL (21), and attitude toward diabetes (22).

Statistical analyses were performed using Statview 5.0. Values are reported as means ± SD or median (range). Groups were compared using t tests or χ2. The effect of time and group-by-time interactions were analyzed with repeated-measures ANOVA. Variables, different between groups and their baseline values, were used as covariates in ANCOVA models. Relationships between variables of interest were analyzed with multiple and forward stepwise linear regression or Spearman rank-order correlation. Statistical significance was accepted at P ≤ 0.05.

Participant characteristics and performance data are presented in Table 1. Participants were obese (63%), displayed metabolic syndrome (82%), had one or more diabetes complications (40%), had comorbidities (predominantly osteoarthritis [84%] and hypertension [76%]), and were recurrent fallers (16%; two or more falls in the past year). At baseline, older age, more comorbidities, higher %BF, poorer cognition, QOL, exercise capacity and muscle power, and slower gait speed and muscle contraction velocity were related to poor balance (P = 0.043 to <0.0001). Similarly, older age, poorer QOL, exercise capacity, balance and muscle power, and slower muscle contraction velocity were related to slower gait speed (P = 0.043 to <0.0001). Forward stepwise regression models revealed that slower muscle contraction velocity was the sole common independent contributor to both balance and gait impairment at baseline.

Balance (P = 0.03) and maximal gait speed (P = 0.005) improved significantly over time, but there were no group-by-time interactions. Habitual gait speed (P = 0.053) and 6-min walk (P = 0.06) showed a trend toward improvement over time. Physiological and health status did not significantly change after the intervention.

Participants with poorer QOL improved balance the most (P = 0.023). By contrast, increased maximal gait speed was associated with better baseline health, muscle function, and exercise capacity. Following stepwise regression, lower baseline blood glucose and %BF independently predicted improved maximal gait speed (r = 0.71, P = 0.0001), accounting for 65% of the variance.

Improvements in balance index (r = 0.34, P = 0.047) and gait speed (maximal gait speed: r = 0.46, P = 0.008; habitual gait speed: r = 0.44, P = 0.011) were significantly correlated with compliance but neither were related to each other (P = 0.90) nor could they be explained by changes in physiological or health status.

We report for the first time the novel and robust relationships between muscle power and contraction velocity and mobility impairment in type 2 diabetes. Muscle contraction velocity was the single characteristic independently associated with poorer balance and gait in this cohort.

After 4 months, Tai Chi provided modest significant improvements in mobility, although not different from sham exercise. The dose and/or movements of the Tai Chi for Diabetes program may not have been sufficient to elicit robust adaptations. Furthermore, the high prevalence of obesity and osteoarthritis may have compromised an optimal training style.

Enhanced balance and gait speed were not related to each other. Compliance, however, was related to improved mobility, suggesting that the observed improvements cannot be solely considered a learning effect. Unmeasured aspects of group participation, such as changes in motor control, socialization, or neuropsychological function, may explain our results.

In conclusion, mobility impairments in an older, obese cohort with type 2 diabetes are associated with low muscle power and may therefore respond more robustly to an exercise intervention specifically designed to improve muscle contraction velocity, such as explosive resistance (power) training.

Table 1—

Baseline characteristics of participants and outcomes after Tai Chi and sham exercise

CharacteristicTai Chi (n =17)
Sham exercise (control) (n = 18)
Change over time P valueGroup effect P value
BaselineFollow-up% changeBaselineFollow-up% change
Age (years) 65.9 ± 7.4   64.9 ± 8.1     
Duration of diagnosed type 2 diabetes (years) 8.5 (0–25)   9.0 (0.7–50)     
Number of comorbidities 6.9 ± 6.7   6.1 ± 8.8     
Cognition (0–30)* 28 (25–30)   27 (23–30)     
Weight (kg) 87.5 ± 13.7 88.1 ± 12.3 −1.1 ± 3.0 80.7 ± 16.1 80.6 ± 16.2 −0.1 ± 1.9 0.2 0.3 
%BF 43.0 ± 4.8 42.7 ± 5.7 −0.6 ± 3.4 37.3 ± 8.4 36.8 ± 9.1 −1.0 ± 2.8 0.1 0.7 
Waist circumference (cm) 106.1 ± 14.6 108.2 ± 13.2 0.5 ± 3.4 98.4 ± 12.6 98.7 ± 12.5 0.4 ± 2.8 0.4 0.9 
Blood glucose (mmol/l) 7.6 (3.9−15.6) 7.5 (5.7−12.5) 7.7 ± 28.8 7.9 (5.6−13.9) 7.4 (5.4−15.4) −3.2 ± 20.4 0.9 0.2 
Daily medications (n7.5 ± 4.0 8.2 ± 4.4 −4.6 ± 19.7 6.4 ± 3.8 6.8 ± 4.0 9.0 ± 5.9 0.9 0.2 
Mobility         
    Balance index (§111.1 ± 23.1 107.3 ± 23.1 2.5 ± 14.9 111.5 ± 22.2 104.1 ± 22.2 5.8 ± 12.6 0.03* 0.5 
    Single leg stance, eyes open (s) 8.96 (0.4−30) 17.9 (0.6−30) 47.7 (−79.2 to 3,473.2) 30 (1.3−30) 24.2 (0−30) 0 (−100 to 407) 0.6 0.4 
    Single leg stance, eyes closed (s) 3.9 (0.4−19.6) 2.8 (0.1−14.0) −22.6 (93.6 to 190.9) 2.2 (0.6−6.0) 2.0 (0−8.3) −23.1 (−100 to 730) 0.2 0.2 
Tandem walk score 19.1 ± 7.0 18.1 ± 8.3 −4.7 ± 27.6 18.5 ± 6.3 17.2 ± 6.2 −5.3 ± 23.4 0.2 0.8 
Habitual gait speed (m/s) 1.0 ± 0.2 1.1 ± 0.2 12.3 ± 27.4 1.1 ± 0.2 1.2 ± 0.3 7.9 ± 26.6 0.053 0.7 
Maximal gait speed (m/s) 1.6 ± 0.3 1.7 ± 0.3 6.6 ± 10.3 1.6 ± 0.3 1.7 ± 0.3 5.9 ± 12.8     0.005 0.9 
Physiological capacity         
    Muscle strength (nmol/l) 91.3 ± 31.5 97.8 ± 24.8 12.9 ± 28.9 89.7 ± 30.3 90.7 ± 33.8 4.9 ± 28.1 0.3 0.5 
    Peak muscle power (W) 215.9 ± 75.4 220.9 ± 64.9 4.8 ± 18.1 221.7 ± 74.5 217.4 ± 74.5 −0.4 ± 16.7 1.0 0.5 
    Peak muscle velocity (rad/s) 2.7 ± 0.8 2.6 ± 0.7 0.8 ± 34.1 2.6 ± 0.8 2.8 ± 0.6 15.5 ± 46.0 1.0 0.3 
    Muscle endurance (number of repetitions) 4 (2−13) 5.5 (0−14) 0 (−100 to 450) 4 (2−11) 3 (0−14) −36.6 (−100 to 200) 0.5 0.5 
    6-min walk distance (m) 474.0 ± 76.1 481.8 ± 83.0 1.7 ± 7.4 456.6 ± 117.8 470.1 ± 118.2 3.6 ± 8.2 0.06 0.6 
CharacteristicTai Chi (n =17)
Sham exercise (control) (n = 18)
Change over time P valueGroup effect P value
BaselineFollow-up% changeBaselineFollow-up% change
Age (years) 65.9 ± 7.4   64.9 ± 8.1     
Duration of diagnosed type 2 diabetes (years) 8.5 (0–25)   9.0 (0.7–50)     
Number of comorbidities 6.9 ± 6.7   6.1 ± 8.8     
Cognition (0–30)* 28 (25–30)   27 (23–30)     
Weight (kg) 87.5 ± 13.7 88.1 ± 12.3 −1.1 ± 3.0 80.7 ± 16.1 80.6 ± 16.2 −0.1 ± 1.9 0.2 0.3 
%BF 43.0 ± 4.8 42.7 ± 5.7 −0.6 ± 3.4 37.3 ± 8.4 36.8 ± 9.1 −1.0 ± 2.8 0.1 0.7 
Waist circumference (cm) 106.1 ± 14.6 108.2 ± 13.2 0.5 ± 3.4 98.4 ± 12.6 98.7 ± 12.5 0.4 ± 2.8 0.4 0.9 
Blood glucose (mmol/l) 7.6 (3.9−15.6) 7.5 (5.7−12.5) 7.7 ± 28.8 7.9 (5.6−13.9) 7.4 (5.4−15.4) −3.2 ± 20.4 0.9 0.2 
Daily medications (n7.5 ± 4.0 8.2 ± 4.4 −4.6 ± 19.7 6.4 ± 3.8 6.8 ± 4.0 9.0 ± 5.9 0.9 0.2 
Mobility         
    Balance index (§111.1 ± 23.1 107.3 ± 23.1 2.5 ± 14.9 111.5 ± 22.2 104.1 ± 22.2 5.8 ± 12.6 0.03* 0.5 
    Single leg stance, eyes open (s) 8.96 (0.4−30) 17.9 (0.6−30) 47.7 (−79.2 to 3,473.2) 30 (1.3−30) 24.2 (0−30) 0 (−100 to 407) 0.6 0.4 
    Single leg stance, eyes closed (s) 3.9 (0.4−19.6) 2.8 (0.1−14.0) −22.6 (93.6 to 190.9) 2.2 (0.6−6.0) 2.0 (0−8.3) −23.1 (−100 to 730) 0.2 0.2 
Tandem walk score 19.1 ± 7.0 18.1 ± 8.3 −4.7 ± 27.6 18.5 ± 6.3 17.2 ± 6.2 −5.3 ± 23.4 0.2 0.8 
Habitual gait speed (m/s) 1.0 ± 0.2 1.1 ± 0.2 12.3 ± 27.4 1.1 ± 0.2 1.2 ± 0.3 7.9 ± 26.6 0.053 0.7 
Maximal gait speed (m/s) 1.6 ± 0.3 1.7 ± 0.3 6.6 ± 10.3 1.6 ± 0.3 1.7 ± 0.3 5.9 ± 12.8     0.005 0.9 
Physiological capacity         
    Muscle strength (nmol/l) 91.3 ± 31.5 97.8 ± 24.8 12.9 ± 28.9 89.7 ± 30.3 90.7 ± 33.8 4.9 ± 28.1 0.3 0.5 
    Peak muscle power (W) 215.9 ± 75.4 220.9 ± 64.9 4.8 ± 18.1 221.7 ± 74.5 217.4 ± 74.5 −0.4 ± 16.7 1.0 0.5 
    Peak muscle velocity (rad/s) 2.7 ± 0.8 2.6 ± 0.7 0.8 ± 34.1 2.6 ± 0.8 2.8 ± 0.6 15.5 ± 46.0 1.0 0.3 
    Muscle endurance (number of repetitions) 4 (2−13) 5.5 (0−14) 0 (−100 to 450) 4 (2−11) 3 (0−14) −36.6 (−100 to 200) 0.5 0.5 
    6-min walk distance (m) 474.0 ± 76.1 481.8 ± 83.0 1.7 ± 7.4 456.6 ± 117.8 470.1 ± 118.2 3.6 ± 8.2 0.06 0.6 

Values of normally distributed data are means ± SD. Non–normally distributed data are median (range).

*

Cognition was assessed by the Mini-Mental State Examination, which uses a scale of 0-30, with scores <24 indicating cognitive impairment (14).

Significant difference between groups at baseline (P = 0.02–0.04).

%BF was determined using bioelectrical impedance analysis (20).

§

Balance index: a lower score indicates better overall balance performance (17).

Tandem walk score equals time to complete course plus number of errors made during the test; a lower score indicates better balance.

P values were determined by factorial ANOVA.

A P value of <0.05 was accepted as statistically significant.

We thank Douglass Hanly Moir Pathology for their sponsorship, Keiser Sports Health for their donation of K400 Electronics for pneumatic-resistance machines, and the participants for their dedication.

1.
Volpato S, Blaum C, Resnick H, Ferrucci L, Fried LP, Guralnik JM: Comorbidities and impairments explaining the association between diabetes and lower extremity disability: the Women’s Health and Aging Study.
Diabetes Care
25
:
678
–683,
2002
2.
Volpato S, Ferrucci L, Blaum C, Ostir G, Cappola A, Fried LP, Fellin R, Guralnik JM: Progression of lower-extremity disability in older women with diabetes: the Women’s Health and Aging Study.
Diabetes Care
26
:
70
–75,
2003
3.
Bruce DGM, Davis WAP, Davis TMED: Longitudinal predictors of reduced mobility and physical disability in patients with type 2 diabetes: the Fremantle Diabetes Study.
Diabetes Care
28
:
2441
–2447,
2005
4.
de Rekeneire N, Resnick HE, Schwartz AV, Shorr RI, Kuller LH, Simonsick EM, Vellas B, Harris TB: Diabetes is associated with subclinical functional limitation in nondisabled older individuals: the Health, Aging, and Body Composition Study.
Diabetes Care
26
:
3257
–3263,
2003
5.
Brandon LJ, Gaasch DA, Boyette LW, Lloyd AM: Effects of long-term resistive training on mobility and strength in older adults with diabetes.
J Gerontol A Biol Sci Med Sci
58
:
740
–745,
2003
6.
Wolf SL, Barnhart HX, Kutner NG, McNeely E, Coogler C, Xu T: Reducing frailty and falls in older persons: an investigation of Tai Chi and computerized balance training: Atlanta FICSIT Group: Frailty and Injuries: Cooperative Studies of Intervention Techniques.
J Am Geriatr Soc
44
:
489
–497,
1996
7.
Schaller KJ: Tai Chi Chih: an exercise option for older adults.
J Gerontol Nurs
22
:
12
–17,
1996
8.
Hain TC, Fuller L, Weil L, Kotsias J: Effects of T’ai Chi on balance.
Arch Otolaryngol Head Neck Surg
125
:
1191
–1195,
1999
9.
Christou EA, Yang Y, Rosengren KS: Taiji training improves knee extensor strength and force control in older adults.
J Gerontol A Biol Sci Med Sci
58
:
763
–766,
2003
10.
Lan C, Lai JS, Chen SY, Wong MK: Tai Chi Chuan to improve muscular strength and endurance in elderly individuals: a pilot study.
Arch Phys Med Rehabil
81
:
604
–607,
2000
11.
Tsang WW, Hui-Chan CW: Effect of 4- and 8-wk intensive Tai Chi training on balance control in the elderly.
Med Sci Sports Exerc
36
:
648
–657,
2004
12.
Hong Y, Li JX, Robinson PD: Balance control, flexibility, and cardiorespiratory fitness among older Tai Chi practitioners.
Br J Sports Med
34
:
29
–34,
2000
13.
Lan C, Lai JS, Chen SY, Wong MK: 12-month Tai Chi training in the elderly: its effect on health fitness.
Med Sci Sports Exerc
30
:
345
–351,
1998
14.
Folstein MF, Folstein SE, McHugh PR: “Mini-Mental State:” a practical method for grading the cognitive state of patients for the clinician.
J Psychiatr Res
12
:
189
–198,
1975
15.
Lam P: Tai Chi for diabetes: designed to help prevent & control diabetes. In
East Action Videos
. Narwee, Australia, Tai Chi Productions,
2001
16.
Pu CT, Johnson MT, Forman DE, Hausdorff JM, Roubenoff R, Foldvari M, Fielding RA, Fiatarone Singh MA: Randomized trial of progressive resistance training to counteract the myopathy of chronic heart failure.
J Appl Physiol
90
:
2341
–2350,
2001
17.
Orr R, de Vos N, Singh N, Ross D, Stavrinos T, Fiatarone Singh M: Power training improves balance in healthy older adults.
J Gerontol A Biol Sci Med Sci
61
:
78
–85,
2006
18.
de Vos NJ, Singh NA, Ross DA, Stavrinos TM, Orr R, Fiatarone Singh MA: Optimal load for increasing muscle power during explosive resistance training in older adults.
J Gerontol A Bio Sci Med Sci
60
:
638
–647,
2005
19.
Guyatt GH, Sullivan MJ, Thompson PJ, Fallen EL, Pugsley SO, Taylor DW, Berman LB: The 6-minute walk: a new measure of exercise capacity in patients with chronic heart failure.
Can Med Assoc J
132
:
919
–923,
1985
20.
Lukaski H, Bolunchuk W, Hall C, Siders W: Validation of tetrapolar bioelectrical impedance method to assess human body composition.
J Appl Physiol
60
:
1327
–1332,
1986
21.
Ware JE, Sherbourne CD: The MOS 36-item short-form health survey (SF-36). I. Conceptual framework and item selection.
Med Care
30
:
473
–483,
1992
22.
Welch G, Beeney LJ, Dunn SM, Smith RBW: The development of the Diabetes Integration Scale: a psychometric study of the ATT39.
Multivariate Exp Clin Res
11
:
75
–88,
1996

P.L. was the creator of the Tai Chi for Diabetes form and producer of its video and is the founder of Tai Chi Productions, which distributes these videos and similar products and services.

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