Morphology, enzyme activities and buffer capacity in leg muscles of Kenyan and Scandinavian runners

Abstract

The study comprises data on 12 Scandinavian runners who had either trained for two weeks in Kenya (n= 6; ∼2000 meters above sea level (m.a.s.l.)) or in Portugal (n= 6; sea level (s.l.)) and on 13 Kenyan runners (9 junior and 4 senior) living and training at ∼2000 m.a.s.l. Muscle biopsies were taken before and after the training camps in the Scandinavian runners and once on the Kenyan runners from the vastus lateralis (v.l.) and the gastrocnemius muscles. Muscle fiber size and composition were similar in the various groups (4.6–5.1 × 103μm2; ST ∼60–70%; FTa 30–40%; FTb < 6.0%) with a tendency for some more (∼5%) FTa fibers in the gastrocnemius muscle. Mean number of capillaries in v.l. varies between 405–493 cap · (mm2)−1, 2.0–2.7 cap · fiber−1, and 4.4–6.2 cap around the various fiber types, with the Kenyan seniors having the highest and the Kenyan juniors the lowest values. All runners had 10–20% more capillaries in their gastrocnemius muscle. Similar levels for citrate synthase (CS) activity were found in the v.l. of the Kenyan seniors and Scandinavian runners, whereas the Kenyan juniors were 10–15% lower. The 3‐hydroxyacyl‐CoA‐dehydrogenase (HAD) activity was 20% higher in the Kenyan than in the Scandinavian runners. In the gastrocnemius muscle, both enzyme activities were 20–50% higher in Scandinavian and Kenyan runners. The ratio for lactate dehydrogenase (LDH) isoform1–2 and isoform4–5 was increased when training at altitude due to a lowering of LDH4–5 and became close to what was observed in the Kenyan runners. Also muscle buffer capacity became increased in the altitude training groups. It is concluded that muscle morphology is quite similar in Scandinavian and Kenyan runners with no effect of training at altitude. Mitochondrial enzyme activities are also unaltered at altitude, but the Kenyan runners have markedly higher HAD activity. Muscle buffer capacity is elevated in the Scandinavian runners training at altitude, and it appears to be an effect of altitude, as no change was observed in the Scandinavian runners training at s.l., which was also the case for the LDH1–2: LDH4–5 ratio as a result of a lowering of LDH4–5 activity.

Economical running strategy for East African distance runners

“…Therefore, their high running economy could not be explained by any of the histochemical and/or biochemical parameters measured from muscle biopsy samples. Consequently, it was clearly concluded, from these reports of Saltin et al 1,2) , that one of the possible reasons for their high mechanical efficiency (or running economy) could be the special biomechanical make-up in their structure and function of the triceps surae muscle-tendon unit (MTU) 1,2) . However, little is known about the mechanical properties of the muscle and tendon in East-African runners and, also, how their neuromuscular system interacts economically and efficiently during running.…”

Rendimiento excelente en las carreras de larga distancia : estudio comparado de corredores kenianos y españoles de alto rendimiento = Excellent performance in long distance races : high performance kenyan and spanish runners comparative research

“…Además, Weston et al (1999) han demostrado en corredores sudafricanos una correlación positiva entre la actividad de la CS y el rendimiento corriendo a un porcentaje estandarizado de la velocidad máxima de la cinta de carrera. Cuando se compara la actividad de la CS entre corredores escandinavos y kenianos de élite de larga distancia, no se encontró ninguna diferencia significativa entre los dos grupos cuando se observó la actividad de los músculos vasto lateral y gastrocnemio (Saltin et al, 1995a).…”

“…Además, una moderada correlación (r = .63) ha sido demostrada entre el número de capilares por mm² y la media de la velocidad en carrera de maratón durante la competición (Sjödin y Jacobs, 1981). Cuando se comparó la capilarización entre los corredores de élite de larga distancia kenianos y daneses, Saltin et al (1995a) observaron una tendencia de una mayor capilarización de los corredores de élite kenianos.…”

“…La diferencia es aún más profunda cuando se corre a intensidades de carrera altas (Saltin et al, 1995a).…”

“…Esto lleva a especular que la economía de carrera superior de los corredores kenianos podría deberse parcialmente a las propiedades particulares de sus músculos involucrados en la carrera (Larsen, 2007, p. 129). Sin embargo, al no encontrarse diferencias significativas en las características musculares entre corredores kenianos de élite y chicos kenianos desentrenados, con respecto a sus homólogos daneses (Saltin et al, 1995a), la posibilidad de considerarlo como un factor diferenciador de la economía de carrera, se debilita.…”