ABSTRACT
Taping is widely used in sports medicine to prevent injury, protect affected sites post injury and relieve pain. However, it is not clear whether taping affects the perception of noxious stimulation because in previous studies, it was difficult to selectively activate Aδ fibers. A recently developed, useful, new tool named intra-epidermal electrical stimulation (IES) can preferentially activate Aδ fibers. We aimed to clarify the effect of taping on pain-related somatosensory evoked potentials (pSEPs) using IES. We recorded pSEPs following IES of the right medial forearm in twelve healthy volunteers. pSEPs were recorded from 9 electrodes on the scalp under control, elastic-taping and white-taping conditions. Under the control condition, subjects relaxed on a comfortable reclining seat without taping, whereas under the taping conditions, they were subjected to taping along the forearm with tension (elastic-taping) and without tension (white-taping). Subjects were asked to assign a visual analog scale (VAS) score after each session. The peak amplitudes of N2-P2 were significantly lower under the elastic-taping and white-taping conditions than those under the control condition. VAS was significantly lower elastic-taping condition than those under the control and white-taping conditions. Moreover, there was a significant positive correlation between the amplitude of N2-P2 and VAS. We revealed that taping along the forearm decreased pSEPs and subjective pain perception under the white-taping and elastic-taping conditions. The underlying mechanism of pain relief was the distraction effect in both taping conditions. In addition, elastic-taping with tension changes afferent inputs mainly from the skin, and this might more effectively decrease the subjective pain perception than that achieved under the white-taping condition.
ABSTRACT
This study aimed to assess the effect of short-interval intracortical inhibition (SICI) before a jump off a platform (pre-set) on drop jump (DJ); the purpose was to investigate the relationship between this activity and performance, and the different effects of SICI on agonist and antagonist muscles during pre-set for jump athletes. Jump athletes (Jumper group, n=13) and Other athletes (Other group, n=9) performed DJ from drop heights of 0.30, 0.45, and 0.60 m). DJ performance was evaluated with DJ-index which was calculated from contact time and jump height. SICI was calculated from motor evoked potentials (MEP) recorded using paired-pulse transcranial magnetic stimulation for the medial gastrocnemius (MG) and tibialis anterior (TA) muscles in 7 jump athletes. Significantly higher DJ performance was observed for the Jumper group at all drop heights, and the Jumper group exhibited greater performance for the highest drop height than the Other groups. Significant decreases in SICI for MG were observed for the Jumper groups, and this decrease in inhibition was more prominent for the highest drop height during pre-set. Furthermore, the correlation between SICI for MG and DJ-index was stronger for increased drop heights, and a significantly positive correlation between these variables was observed at a height of 0.60 m. However, the SICI during the pre-set for TA exhibited no significant change under any of the conditions. The results of the present study suggest the importance of selective disinhibition of brain areas associated with the agonistic muscles during pre-set for higher DJ performance.
ABSTRACT
Taping is widely used by sports trainers to prevent injury and to protect affected sites post-injury. However, it is not clear whether taping affect the perception of somatosensory stimulation. We sought to clarify the effect of taping on somatosensory stimulation using somatosensory evoked potentials (SEPs). We recorded SEPs following transcutaneous electrical stimulation of the right medial forearm in ten healthy volunteers. SEPs were recorded from 9 electrodes on the scalp under control, elastic-taping and white-taping conditions. Subjects relaxed on a comfortable reclining seat without taping in the control condition, while they were subjected to taping along the muscle of forearm with tension (elastic-taping) and without tension (white-taping) in the taping conditions. Results showed that the peak amplitude of N140 did not differ significantly among the three conditions but the peak amplitude of P250 was significantly lower in the elastic-taping condition than control and white-taping conditions. Elastic-taping with tension along the muscles changes various afferent inputs from muscle spindle or skin, and this may affect the perception of somatosensory stimulation.
ABSTRACT
This study was conducted to assess body composition and somatotype in elite female distance runners and to investigate the relationship between body composition and somatotype. Nine elite female distance runners (21.6±2.7 yrs) and 10 female college students (21.4±0.5 yrs) as a control group participated in this study. Body composition was estimated in terms of total body water based on the analysis of dilution of orally ingested deuterium oxide (D<SUB>2</SUB>O) in urine. Somatotype was estimated by Heath-Carter method.<BR>The skinfold thickness in distance runners were significantly thinner at 14 sites than those of the control group. The mean subcutaneous fat in distance runners was 4.1±1.6 kg (8.6±2.8%), which was significantly lower than that of the control group (9.4±3.0 kg & 17.2±3.8%) . The mean internal fat in distance runners was 7.2±2.0 kg (15.5±3.5%), which tended to be lower than that of the control group (8.2±1.5 kg & 15.4±2.2%) . The mean fat mass and percentage of body fat in distance runners were 11.3±3.1 kg and 24.1±4.7%, respectively, which were siginificantly lower than those of the control group (17.6±4.2 kg & 32.6±5.2%) . On the other hand, somatotype scores in distance runners were 2.35-2.32-3.82, suggesting more ectomorphic. In addition, fat mass positively correlated with the first component (r=0.890-0.916, p<0.05), and negatively correlated with the third component (r=-0.635--0.818, p<0.05) . The subjects who were more ectomorphic had less fat mass. However, the second component that was mesomorphic had no significant correlation with lean body mass. And the mean lean body mass in distance runners was almost the same as that of the control group (35.1±2.5 kg & 36.1±3.5 kg) .<BR>The results of this study suggest that although endurance training done by elite female distance runners does not increase their lean body mass, it has a great influence on their subcutaneous fat.
ABSTRACT
Blood lactate disappearance in endurance-trained men (ET) and untrained men (UT) was investigated by application of recovery exercise with high relative intensity. Blood lactate was measured in five male long-distance runners as ET and in seven male relatively active students as UT, using a cycle ergometer (60 rpm) . Two kinds of recovery exercise were performed at intensities of 70% and 40% Vo<SUB>2</SUB>max for 20 min followed by main exercise at 90% Vo<SUB>2</SUB>max for 3 min. The rate of blood lactate removal was calculated by linear regression of time (min) against blood lactate (mmol·<I>l</I><SUP>-1</SUP>) at 5, 10, 15 and 20 min during recovery exercise. Values of blood lactate at 10, 15 and 20 min during recovery exercise at 70% Vo<SUB>2</SUB>max were significantly more reduced in ET than in UT (P<0.05, P<0.01) . There was, however, no significant difference between ET and UT during recovery exercise at 40% Vo<SUB>2</SUB>max. The rate A of blood lactate removal during 70% recovery exercise was significantly greater in ET (0.2730±0.0920mmol·<I>l</I><SUP>-1</SUP>.min<SUP>-1</SUP>) than in UT (0.0520±0.1010mmol·<I>l</I><SUP>-1</SUP>·min<SUP>-1</SUP>) (P<0.01), but there was no significant difference in the rate between ET and UT during 40% recovery exercise. The rate B of blood lactate removal during 70% recovery exercise was significantly higher in ET (0.3770±0.08000 mmol·<I>l</I><SUP>-1</SUP>· min<SUP>-1</SUP>) than in UT (0.1163±0.14416 mmol·<I>l</I><SUP>-1</SUP>·min<SUP>-1</SUP>) (P<0.01), but there was no significant difference in the rate between ET and UT during 40% recovery exercise.<BR>In conclusion, the present data indicate that endurance-trained men possess more pronounced capability for blood lactate removal during recovery exercise at high relative intensity.
ABSTRACT
A study was conducted to assess the relationship between CO<SUB>2</SUB> excess due to lactic acid production during exercise and endurance performance in order to clarify the availability of CO<SUB>2</SUB> excess as an index of endurance capacity. Four healthy males (control group; CON) aged 21-24 years, and six male long-distance runners (LDR) aged 18-22 years, were subjected to incremental maximal testing on a cycle ergometer and 12-min exhaustive track running. The results obtained are summarized as follows.<BR>1) Mean values (±SD) of CO<SUB>2</SUB> excess (m<I>l</I>) were 3, 442±677 m<I>l</I> for LDR and 2, 667±437 m<I>l</I> for CON, respectively. On the other hand, the mean value of CO<SUB>2</SUB> excess per unit body weight (CO<SUB>2</SUB> excess/w) obtained in LDR (59.1±9.07 m<I>l</I>⋅kg<SUP>-1</SUP>) was significantly higher than that in CON (40.3±3.54 m<I>l</I>⋅kg<SUP>-1</SUP>) (p<0.01) .<BR>2) The ratio of CO<SUP>2</SUP> excess/w to ΔLA (the difference between blood lactate at 1 min after exercise and that at rest) showed a tendency to be higher in LDR (5.59±1.16 m<I>l</I>⋅kg<SUP>-1</SUP>⋅mmol<SUP>-1</SUP>) than in CON (4.46±0.69 m<I>l</I>⋅kg<SUP>-1</SUP>⋅mmol<SUP>-1</SUP>) . However, there was no significant difference between these two groups in the ratio of CO<SUP>2</SUP> excess/w to ΔLA.<BR>3) The CO<SUP>2</SUP> excess/w (m<I>l</I>⋅kg<SUP>-1</SUP>) was significantly related to Vo<SUB>2</SUB>max (r=0.813, p<0.01) and Vo<SUB>2</SUB>AT (r=0.892, p<0.001), respectively. Moreover, CO<SUB>2</SUB> excess/w was significantly correlated with ΔHCO<SUB>3</SUB>- (the difference between blood bicarbonate at l min after exercise and that at rest) (r=0.649, p<0.05) .<BR>4) The CO<SUB>2</SUB> excess (m<I>l</I>) and CO<SUB>2</SUB> excess/w (m<I>l</I>⋅kg<SUP>-1</SUP>) were significantly correlated with 12-min exhaustive running performance (r=0.715, p<0.05, r=0.933, p<0.001), as was the ratio of CO<SUB>2</SUB> excess/w to d LA (r=0.671, p<0.05) .<BR>5) From these results, it was suggested that the CO<SUB>2</SUB> excess/w and the ratio of CO<SUB>2</SUB> excess/w to ΔLA could be important factors related to performance of endurance exercise (i. e., 3, 000-5, 000 m running) accompanied by blood lactate accumulation.