Table 1.

Prevalence of skeletal muscle atrophy.

Condition	Affected Muscle	Main Findings	References
High-Fat Diet	EDL muscle	More than 12-week HFD induced degradation of fast-twitch muscle fibers (EDL).	[16,20]
	Gastrocnemius muscle	Long-term HFD decreased mitochondrial enzyme gene expression and activity in the gastrocnemius muscle.	[19]
	Soleus muscle	Three-week HFD induced denervation muscle atrophy in soleus muscle.	[17]
	EDL and soleus muscles	Shift from type IIb fiber to type IIa fiber was observed in the ob/ob group in the EDL muscles, whereas the opposite was observed in the soleus muscles.	[186]
Obesity	Soleus and EDL muscles	The absolute isometric force of the obese soleus muscles was significantly greater than that of lean controls; however, the maximal isometric stress and normalized power output of both obese soleus and EDL muscles were reduced.	[54]
	Soleus and EDL muscles	Despite the increased muscle mass in the HFD-induced obese soleus and EDL muscles, muscle strength remained unchanged.	[55]
	EDL, gastrocnemius, and plantaris muscles	EDL, gastrocnemius, and plantaris muscles were significantly smaller in the obese animals compared to lean counterparts.	[47]
	EDL and soleus muscles	EDL and soleus muscle mass were lower in the obese Zucker rats than lean controls, concomitant with reduced fiber area.	[187]
Diabetes Mellitus	Leg and appendicular muscles	T2DM was associated with accelerated loss of leg muscle strength and quality in older adults.	[100,188]
	Appendicular, trunk, and thigh muscles	Older adults with either diagnosed or undiagnosed T2DM showed excessive loss of muscle mass.	[76]
	Total and appendicular muscles	There was a greater loss in total and appendicular lean muscle mass in older men with untreated DM compared to normoglycemic counterparts.	[189]
	Gastrocnemius	Mice with T1DM phenotype showed a significantly lower gastrocnemius muscle fiber cross-sectional area.	[74]
	Ankle flexors, ankle extensors, knee flexors, elbow, and wrist	Significant reduction was observed in the muscle strength of the ankle flexors (17%), ankle extensors (14%), and knee flexors (14%) in patients with T2DM. Elbow and wrist muscle strengths were preserved.	[102]
	Quadriceps	DM status was significantly associated with reduced gait speed. Insulin-dependent older adults had significantly reduced quadricep strength and power.	[103]
	Hand grip and knee extensor	Older adults with T2DM had lower muscle strength, but not muscle mass compared with non-diabetic counterparts.	[107]
Sarcopenia	Gastrocnemius, EDL, and soleus muscles	Muscle atrophy was greatest in aging gastrocnemius muscles and intermediate in aging EDL and soleus muscles.	[117]
	Leg circumference	The leg circumference of >40 years of age was less than that of <40 years of age.	[190]
	Abdomen, lower extremities	Muscle thickness in the abdomen and lower extremities decreased significantly in Japanese men aged 60 years and older.	[191]
	Hand grip and upper and lower extremities	Decreased hand grip strength and low gait speed were observed in elderly individuals with cognitive impairment and dementia. Reductions in muscle strength of both upper and lower extremities were higher in the AD group.	[143]
	Tibialis anterior muscle	There was a reduction in axonal innervation of transgenic mice compared to the wild-type control.	[138]
Cancer Cachexia	Soleus and gastrocnemius muscles	Muscles of MAC16 injected mice showed an increased lysosomal protease activity.	[164]
	Quadriceps	Injection of IL-6 in mice with colon cancer induced systemic muscle wasting.	[171]
	Gastrocnemius muscle	There was a significant nitrogen loss with a depressed muscle protein synthesis and increased protein degradation during cancer cachexia.	[192]
	Rectus muscle	Mean muscle fiber diameter in cachectic cancer patients was reduced by about 15% compared to non-cachectic cancer patients.	[163]
Heart Failure	Type I fibers	Patients with chronic HF developed significant abnormalities in skeletal muscle, reflecting a decreased oxidative capacity in type I fibers.	[181]
	Handgrip and quadriceps	Patients with chronic HF presented reduced muscle mass and decreased exercise capacity in treadmill performance and walking exercise tests.	[179]
	Quadriceps	Myofibril contractile function was strongly related to insulin sensitivity in HF patients, independent of muscle size.	[185]

Abbreviations: T2DM, type 2 diabetes mellitus; DM, diabetes mellitus; STZ, streptozotocin; T1DM, type 1 diabetes; EDL, extensor digitorum longus; HFD, high-fat diet; ob/ob, obese mouse; AD, Alzheimer’s disease; IL-6, interleukin-6; HF, heart failure.