The purpose of this study was to examine the effects of submaximal cycling at different exercise intensities on maximal isometric force output of the non-exercised elbow flexor muscles after the cycling. A total of 8 healthy young men performed multiple maximal voluntary contractions by the right elbow flexion before, immediately after, 5 min after, and 10 min after a 6-min submaximal cycling at ventilatory threshold (LI), 70% (MI), and 80% (HI) with both arms relaxed in the air. Force and surface electromyogram (EMG) of the right biceps brachii muscle during the multiple MVCs, blood lactate concentration ([La]), cardiorespiratory responses, and sensations of fatigue for legs (SEF-L) were measured before, immediately after, 5 min after, and 10 min after the submaximal cycling with the three different exercise intensities. Immediately after the submaximal cycling, [La], cardiorespiratory responses, and SEF-L were enhanced in proportion to an increase in exercise intensity of the cycling. Changes in force and EMG activity during the multiple MVCs were not significantly different across the three conditions. The findings imply that group III/IV muscle afferent feedback after the submaximal cycling does not determine the magnitude of MVC force loss of the non-exercised upper limb muscles.
Authors:T. Matsuura, H. Takenawa, T. Suzuki, R. Hirota and K. Sasaki
The lowest retention values of51Cr hot atom in various forms of the -diketonetype complexes, Cr(bzac)3, Cr(dpm)3 and Cr(dbm)3, as well as Cr(acac)3 as a reference, were obtained in the experimental condition in which they are regarded as the primary retentions. From these retention values, the threshold energies for producing a hot atom, the appearance energies, were estimated using the calculated relationship between the primary retention and appearance energy, which was obtained by the recoil energy spectra computed by the method recently developed by us. The appearance energy increased steeply with increasing molecular weight of the complex. A theoretical interpretation for this result was attempted by setting a model in which a hot atom is produced in the center of the complex and receives the stopping action by the surrounding ligand molecule. The agreement between the observed and calculated values was good.
Authors:T. Yano, T. Yunoki, R. Matsuura, T. Arimitsu and T. Kimura
The purpose of the present study was to examine the effect of change in blood volume in skin plus active muscle on heart rate drift during moderate exercise and heavy exercise for 30 min. Total hemoglobin concentration (Total Hb) in the vastus lateralis muscle plus its skin was determined by near-infrared spectroscopy. Total Hb significantly increased and remained stable from 20 min in moderate exercise and from 10 min in heavy exercise. Heart rate (HR) rapidly increased until 3 min and showed a steady state in moderate exercise. HR at 30 min was significantly higher than that at 3 min in moderate exercise. HR rapidly increased until 3 min and then gradually but significantly increased in heavy exercise. Increase in total Hb was not significantly related with HR after 3 min of exercise when HR was around 120 beats per min in moderate exercise. Increase in total Hb was significantly related with HR from 3 min to 10 min in the heavy exercise (correlation coefficients ranged from 0.959 to 0.702). It is concluded that an increase in the blood volume in skin plus active muscle is not simply associated with HR drift.
Authors:R. Matsuura, T. Arimitsu, T. Yunoki, T. Kimura, R. Yamanaka and T. Yano
The purpose of the present study was to determine the effects of deception for exercise intensity on surface electromyogram (SEMG) activity and blood lactate concentration during intermittent cycling exercise (ICE) tests. Sixteen healthy male were randomly assigned to two groups who completed two ICE [three 4-min cycling at 80% peak power output (PPO) with 3-min passive recovery periods followed by exhaustive cycling] tests (ICE-1 and ICE-2). The experimental group (ICED) was deceived of the actual cycling intensity, while the control group (ICEC) was informed of the actual protocol in ICE-2. In ICE-1, both groups were informed of the actual protocol. In ICE-2, root mean square (RMS) calculated from SEMG during submaximal cycling was significantly higher in the ICEC than in the ICED and blood lactate concentration ([La−]) was significantly higher in the ICEC than in the ICED. In particular, the difference in RMS between the groups was also observed during the first 4-min cycling, in which there was no difference in [La−] between the groups. These results suggest that the CNS modulates skeletal muscle recruitment due to the prior deception for exercise intensity.