Mixed
Standard planimetric muscle models that assume constant muscle thickness and straight fibers significantly underestimate changes in pennation angle and fiber length during contraction, leading to inaccurate estimates of muscle force and joint moment.
When calculating muscle force or joint moments for the calf muscles (gastrocnemius and soleus) during strong contractions, do not assume the muscle stays the same thickness. The muscle belly thickens, fibers shorten, and pennation angle increases significantly. Using simple geometric models that ignore these changes will underestimate the actual force produced by these muscles by approximately 10-15%.
The findings of the study indicate that the mechanical output of muscle as estimated by the model used may be unrealistic due to errors in estimating the changes in muscle architecture during contraction compared with rest.
Why this rating
In vivo human measurements with rigorous statistical analysis (P<0.01) comparing actual vs. modeled values.
Source
<i>In vivo</i> measurements of the triceps surae complex architecture in man: implications for muscle function
Constantinos N. Maganaris et al. · The Journal of Physiology · 1998
DOI 10.1111/j.1469-7793.1998.603be.x
Related findings · Mixed
- Bariatric surgery (VSG and RYGB) is the most effective and sustainable treatment for obesity, producing marked and sustained weight loss that non-surgical interventions cannot match.Strong
- Severely protein-deficient diets (2–3% energy) induce lean body mass loss and metabolic imbalance, whereas adequate protein intake (0.66 g/kg/d minimum) is a prerequisite for maintaining muscle, bone, and physiological function.Strong
- For patients with Class III obesity (BMI >39.9 kg/m2), metabolic bariatric surgery (MBS) is significantly more effective than any currently approved medication, with BilioPancreatic Diversion (BPD) showing the highest estimated weight loss.Strong
This is one finding among thousands. Every one is graded and traced to its source, so you can see what the evidence actually supports. Browse the research →