The gastrocnemius muscle, a key component of the calf, plays a crucial role in activities like running and jumping. Recent studies have explored the structural differences in the gastrocnemius muscle-tendon complex between different ethnic groups, particularly African Americans and Caucasians, to understand their potential impact on athletic performance.
One such study compared international-level Kenyan runners to non-trained white males, matching them for height. The researchers measured various anthropometric and kinematic outcomes, including Achilles tendon length, power, contact time, and rebound height. The results indicated that the Kenyan athletes had longer Achilles tendons, shorter contact times during hopping, longer flight times, greater rebound height, and greater jumping power. This suggests greater elasticity in the Kenyan calves, which could improve running economy by allowing faster running at a lower oxygen cost.
Kenyan athletes vs control group. Source: sportsscientists.com
However, it's important to note that this study doesn't definitively prove what makes Kenyan runners superior to European/Caucasian runners. The comparison may be skewed because it contrasts highly trained athletes with untrained individuals. The observed differences might reflect the advantages of training and athleticism rather than inherent ethnic or racial traits.
The Importance of Control Groups
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To accurately assess the impact of ethnicity on running ability, the true control group should consist of performance-matched athletes from different regions, such as Europe or America. If differences persist even among performance-matched runners, it could reveal that similar performance levels can result from varying combinations of "input" characteristics.
Alternative Research Approaches
To address the limitations of comparative research, alternative approaches can be considered. One option is to compare completely untrained individuals from different ethnic backgrounds to eliminate the training confounder. Another is to study children, as Saltin did in a previous study, although even at a young age, lifestyle differences can be significant.
The "Unique Factor Approach"
The search for a single "unique factor" that explains the dominance of certain ethnic groups in sports is likely to be futile. It's improbable that Kenyans possess a magical attribute that the rest of the world lacks. Instead, the focus should be on whether a collection of beneficial factors is present with a greater frequency in one group than another.
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The Numbers Effect: A Theory for Kenyan Dominance
One theory suggests that elite runners possess a combination of characteristics, including economy, maximal oxygen uptake, biochemistry, calf elasticity, Achilles tendon length, and muscle power. While individuals worldwide may possess these characteristics, they might be more prevalent in certain populations, such as those in East Africa.
Out of a group of untrained East African "aspirants," more may possess the right collection of running-positive attributes than a similarly trained group elsewhere. When combined with the right culture and training environment, this higher prevalence could explain the emergence of numerous world-class athletes from Kenya, Ethiopia, and Eritrea.
The Role of Tendon Length and Muscle Composition
Tendon Length: Longer Achilles tendons appear to generate more power because they stretch more. During the landing phase of running, tendons, particularly the Achilles tendon, stretch. During the push-off phase, energy from the stretched Achilles tendon adds to the force generated by the contracting muscle.
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The runner with the longer Achilles tendon gets more of that needed force from the tendon’s elastic recoil, requiring the muscle to generate less force and use less energy while running at that speed. In previous studies, Hunter showed that longer Achilles tendons also produced more energy efficiency in walking. "We found a strong correlation between tendon length and running economy, or energy expenditure, in our subjects at both the six and seven mph running speeds and at a walking pace of three mph," said Hunter.
Muscle Composition: Skeletal muscle architectural characteristics and body composition were studied in 13 black and 31 white male college football players. There were no significant differences between blacks and whites in isolated muscle thickness, pennation angle, and fascicle length in the triceps long head, vastus lateralis, and gastrocnemius medialis muscles. However, blacks had a significantly greater quadriceps, hamstrings, biceps, and abdomen muscle thickness than those of whites.
Ethnic Differences in Muscle-Tendon Complex
A study comparing African American and Caucasian sedentary women found that African American women had shorter gastrocnemius muscles and longer tendons. They also performed walking more economically. Tendon length was the only variable related to walking economy. No ethnic differences were observed in walking economy after adjusting for tendon length. Data show gastrocnemius tendon length is related to level walking and longer gastrocnemius tendons may partly explain more economical walking in African American women.
| Characteristic | Kenyan Athletes | White Males |
|---|---|---|
| Achilles Tendon Length | Longer | Shorter |
| Contact Time (Hopping) | Shorter | Longer |
| Flight Time (Hopping) | Longer | Shorter |
| Rebound Height | Greater | Smaller |
| Jumping Power | Greater | Smaller |
Key Differences Between Kenyan and White Participants
