The aim of the study was to determine whether the rapid ramp protocol in cycling induces low frequency fatigue (LFF) in quadriceps femoris muscle and if post-tetanic potentiation compensates for it. Handball players 15-16 years of age participated in the experiment (n=12). They had been engaged in regular training for 3-5 years. Maximal voluntary contraction force (MVC) decreased (p<0.05) from 71.1±13 kg to 66.3±5.2 kg after the cycling. The counter squat jump at the same time remained almost unchanged (35.1±5 and 34±6 cm). There was a considerable decrease (p<0.01) in single twitch, 10 and 20 Hz contraction force up to 62±15%, 62±16% and 70.1±12% of the initial respectively. At the same time 50 Hz contraction force consisted of 89±10% (p<0.05) of the initial. It caused the reduction of 20 and 50 Hz contraction force ratio (from 0.72±0.06 to 0.56±0.08) that was considered to be an indicator of LFF. The force-time integral measured in tetanic contractions exhibited profound reduction (p<0.01) at any stimulation frequency employed. In conclusion, the rapid ramp protocol in cycling induced low frequency fatigue (LFF) in quadricep femoris muscle, however, there was no post-tetanic potentiation.
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