Table 1.
Summary of studies between 2008–2017 on factors affecting IMAT
| Research topic, participants | Study design, methods, outcome measures | Results | Conclusion | Investigators |
|---|---|---|---|---|
| Physical activity 11 men, 31 women 70–89 years |
RCT (PA or ED) 12 month. IMAT from mid-thigh CT. | Muscle strength decreased in ED, but maintained in PA. No significant increase in IMAT in PA. SQF no difference between groups. | PA can prevent loss of strength and IMAT accumulation. | Goodpaster et al.36) |
| Race and obesity 1,105 Caucasian 518 Afro-Caribbean men Mean age 65 years |
BMI, DXA, SQF, and pQCT of calf muscle. | Afro-Caribbeans had greater IMAT and lower SQF at all levels of adiposity. Difference in IMAT, SQF independent of age, height, calf skeletal muscle, and total adipose tissue. |
IMAT greater among African than Caucasian men despite lower adiposity. IMAT associated with T2D in both groups. | Miljkovic et al.42) |
| Aging and weight gain n=1,678 men and women Mean age 73 years |
Health ABC cohort study. Thigh CT scan, CSA muscle, strength, muscle quality. | Weight gain did not prevent loss of muscle strength. IMAT increased with age in men and women. IMAT increased with weight gain, loss, or weight stability. | Aging associated with decreased strength and quality regardless of body weight changes. IMAT changes independent of weight changes. | Delmonico et al.43) |
| Age and eccentric resistance exercise 88 men and women Age range 30–67 years |
Two aims. Observe IMAT change with age and 3 nonconsecutive days/wk for 12-week eccentric resistance training (age 55 and over). Thigh MRI. | Increasing IMAT with age. 11% decrease in thigh IMAT and 7% increase in thigh lean tissue in response to eccentric training. |
Eccentric resistance training decreased thigh IMAT in a range of adults with metabolic and mobility deficits. | Marcus et al.40) |
| Exercise and muscle location 45 men and women Age 56–64 years. Obese, diabetic, or diabetic with peripheral neuropathy |
IMAT right calf by MRI, 6 min. walk test and PPT. | Gastrocnemius muscle highest IMAT and volume. No group differences. Calf IMAT inversely related to 6 min walk and PPT. | Calf IMAT muscle specific and associated with poorer physical performance. | Tuttle et al.45) |
| Weight loss and physical function 36 overweight to moderately obese, sedentary older adults |
RCT comparing PA plus weight loss (PA+WL) or PA plus successful aging education (PA+SA) program. DXA, CT Biodex, SPPB. |
6 months, PA+WL lost greater thigh fat and muscle area; PA+WL lost 12.4% strength; PA+SA lost 1.0%. Muscle fat infiltration decreased significantly in PA+WL. Thigh fat area decreased 6-fold compared to lean area in PA+WL. Change in SPPB inversely correlated with change in fat, but not with change in lean or strength. | Weight loss resulted in additional functional improvements over exercise alone, primarily due to loss of body fat. | Santanasto et al.37) |
| 70 older adults with fall history Mean age 73.4±6.3 years |
Resistance, endurance, and balance exercise 3 nonconsecutive days/wk for 12 weeks. MVC, thigh MRI to determine cross-sectional area of lean tissue and IMAT. MQ=force per unit area of lean tissue. Changes in MQ, lean and IMAT. |
No significant changes in lean or IMAT in any group with training. MQ increased only in baseline low IMAT group. Middle and high IMAT groups did not demonstrate a significant change in MQ following training. | High thigh IMAT blunted the adaptive MQ response to training. | Yoshida et al.28) |
| Dietary restriction and exercise (DR+E) in obese older adults 27 sedentary obese women Mean age 63.6±5.6 years |
RCT 6 months DR+E or ED. Thigh and calf muscle SQF, and IMAT by MRI. Physical function by long-distance corridor walk and knee extension strength. |
DR+E significantly reduced body mass. Thigh and calf muscle volumes responded similarly between groups. Knee extension strength not changed by DR+E, but trend increased walking speed in the DR+E group. DR+E reductions in SQF and IMAT within calf, but not the thigh, associated with faster walking speed. | DR+E preserved lower extremity muscle size and function and reduced regional lower extremity adipose tissue. Reductions in calf SQF and IMAT associated with positive adaptations in physical function. | Manini et al.38) |
| CR for weight loss and RT on muscle and physical function 126 overweight/obese men and women. Mean age 65–79 years |
RCT of 5-month progressive, 3 d/wk, moderate-intensity RT with weight loss (RT+CR) or RT without weight loss (RT). Biodex maximal knee strength; muscle power. DXA and CT muscle quality, overall physical function, and total body and thigh composition. |
Fat mass, % fat, and all thigh fat volumes decreased in both groups. Only RT+CR group lost lean mass. Post-intervention body and thigh composition were all lower with RT+CR except IMAT. Lower % baseline fat and IMAT had greater improvement in the 400-m walk, knee strength and power. |
RT improved body composition (including reduced IMAT) and muscle strength and physical function. Higher baseline adiposity had less improvement. | Nicklas et al.39) |
| PA and weight loss. 36 overweight to moderately obese older adults. Mean age 70.6±6.1 years |
12-month pilot RCT (PA+WL) or PA plus SA education. PA was treadmill walking supplemented with lower extremity resistance and balance training. WL based on Diabetes Prevention Project with 7% weight loss by cutting fat calories. CT and DXA. VAT and thigh IMAT. SPPB |
Decreased IMAT and VAT significantly associated with improved SPPB independent of change in total fat mass. PA+WL improved SPPB, whereas PA+SA did not. No intergroup differences. | Decreases in IMAT and VAT important mechanisms underlying improved function following intentional weight loss plus physical activity. | Santanasto et al.41) |
| Nutritional supplementation and physical activity. 149 mobility limited and vitamin D deficient older adults. 46.3% women Mean age 78.5±5.4 years. |
Six-month trial. All participated in a PA program of walking, lower-extremity strength exercises, balance, and flexibility. Randomized to daily nutritional supplement (150 kcal, 20 g whey protein, 800 IU vitamin D, 119 mL beverage) or placebo (30 kcal, non-nutritive, 119 mL). DXA CT thigh composition and muscle strength, power, and quality. |
Both groups demonstrated improvements in muscle strength, body composition, and thigh composition. Nutritional supplementation led to further losses of IMAT and increased normal muscle density. | Six months of physical activity resulted in improvements in body composition, SQF, IMAT and strength. Addition of nutritional supplement showed further declines in IMAT and improved muscle density. | Englund et al.44) |
IMAT, intermuscular adipose tissue; RCT, randomized controlled trial; PA, physical activity; ED, education; CT, computed tomography; SQF, subcutaneous fat; BMI, body mass index; DXA, dual energy X-ray absorptiometry; pQCT, peripheral quantitative computed tomography; T2D, type 2 diabetes; ABC, aging and body composition; CSA, cross sectional area; MRI, magnetic resonance spectroscopy; PPT, physical performance test; WL, weight loss; SA, successful aging; SPPB, short physical performance battery; MVC, maximal voluntary contraction; MQ, muscle quality; DR, dietary restriction; E, exercise; RT, resistance training; CR, caloric restriction; VAT, visceral adipose tissue.