H. Tanaka et T. Swensen, IMPACT OF RESISTANCE TRAINING ON ENDURANCE PERFORMANCE - A NEW FORM OF CROSS-TRAINING, Sports medicine, 25(3), 1998, pp. 191-200
In accordance with the principles of training specificity, resistance
and endurance training induce distinct muscular adaptations. Endurance
training, for example, decreases the activity of the glycolytic enzym
es, but increases intramuscular substrate stores, oxidative enzyme act
ivities, and capillary, as well as mitochondrial, density. In contrast
, resistance or strength training reduces mitochondrial density, while
marginally impacting capillary density, metabolic enzyme activities a
nd intramuscular substrate stores (except muscle glycogen). The traini
ng modalities do induce one common muscular adaptation: they transform
type nb myofibres into IIa myofibres. This transformation is coupled
with opposite changes in fibre size (resistance training increases, an
d endurance training decreases, fibre size), and, in general, myofibre
contractile properties. As a result of these distinct muscular adapta
tions, endurance training facilitates aerobic processes, whereas resis
tance training increases muscular strength and anaerobic power. Exerci
se performance data do not fit this paradigm, however, as they indicat
e that resistance training or the addition of resistance training to a
n ongoing endurance exercise regimen, including running or cycling, in
creases both short and long term endurance capacity in sedentary and t
rained individuals. Resistance training also appears to improve lactat
e threshold in untrained individuals during cycling. These improvement
s may be linked to the capacity of resistance training to alter myofib
re size and contractile properties, adaptations that may increase musc
ular force production. In contrast to running and cycling, traditional
dry land resistance training or combined swim and resistance training
does not appear to enhance swimming performance in untrained individu
als or competitive swimmers, despite substantially increasing upper bo
dy strength. Combined swim and swim-specific 'in-water' resistance tra
ining programmes, however, increase a competitive swimmer's velocity o
ver distances up to 200m. Traditional resistance training may be a val
uable adjunct to the exercise programmes followed by endurance runners
or cyclists, but not swimmers; these latter athletes need more specif
ic forms of resistance training to realise performance improvement.