The acute effect of mouth only breathing on time to completion, heart rate, rate of perceived exertion, blood lactate, and ventilatory measures during a high-intensity shuttle run sequence.

This study investigated the effect of restricting nasal breathing during a series of 20-m shuttle runs. Ten male participants (mean age = 21.7 ± 2.4 years, height = 1.80 ± 0.62 m, mass = 79.2 ± 10.4 kg, sum of 4 skinfolds = 54.5 ± 7.8 mm) were required to either (a) dive on the ground and complete a rolling sequence (condition = GRD) or (b) complete the shuttles while staying on their feet and tagging the line with 1 foot, at the end of each 20-m segment (condition = STD). The shuttle runs were completed with and without a nose clip (no clip = nc; with a clip = clip) under 4 different trial conditions in a randomized order (GRDnc; GRDclip; STDnc; and STDclip), requiring the participants to return on 4 separate occasions separated by 5-7 days. Heart rate was recorded throughout each trial, and the rate of perceived exertion (RPE) was measured at the completion of each shuttle sequence. Pretrial and posttrial lactate and respiratory function measures were also recorded. The general linear model with repeated measures analysis indicated that there was a significant effect for Roll (GRD > STD) (p ≤ 0.05) but not for Clip (p > 0.05) on total time to completion in the trials. There was no significant interaction of the conditions (Roll × Clip) for RPE (p > 0.05). Similarly, there was no significant effect for blood lactate measured 3 minutes post the last shuttle for Roll (p > 0.05) and Clip (p > 0.05). There was a significant main effect on the HR across all 6 time points (i.e., pre, intervals 1-4 and 10 minutes post) (p ≤ 0.05) and for Roll (GRD > STD) (p ≤ 0.05), but not for Clip (p > 0.05). No significant effect of Roll or Clip was found for any of the recorded ventilation measures (p > 0.05). On the basis of these findings, the use of restricted nasal breathing, while performing a high-intensity shuttle sequence as a method of increasing the acute training effect on athletes, is questionable, so strength and conditioning coaches should carefully consider their rationale for using such a training strategy.

[Effect of acupuncture of different acupoints on immune function in rats with exhausted swimming].

OBJECTIVE: To observe the effect of acupuncture of "Zusanli" (ST 36) on immune function in progressively exhausted swimming rats so as to reveal its mechanism underlying improvement of strenuous exercise. METHODS: Thirty-two SD rats were randomly allocated into control group, strenuous exercise (model) group, acupuncture-Xuehai (SP 10) group, Acupuncture-Zusanli (ST 36) group (n = 8/group). The rats were forced to have a swimming in a water tank for 15-90 min in the first 8 days (once daily), then, a progressively exhausted load swimming 1 - 3 times everyday from day 9 to 13. Bilateral SP 10 and ST 36 were punctured with filiform needles and stimulated with uniform reinforcing and reducing manipulation, once daily, after termination of the swimming and for 13 days. Serum interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) contents were assayed by using enzyme linked immunosorbent assay. The rat's body weight and the spleen weight were weighted by using an electronic balance for calculating the spleen index (spleen weight /body weight x 100%) after killing the rat under deep anesthesia. RESULTS: Compared with the model group, the time of swimming-induced exhaustion appearing at the first time from day 9 to day 13 in the SP 10 and ST 36 groups was apparently lengthened (P < 0.01). No significant difference was found between SP 10 and ST 36 groups in the time of swimming-induced exhaustion appearing at the first time of the forced swimming. Compared with the control group, the spleen index, serum IFN-gamma contents and IFN-gamma/IL-4 in the model group were decreased significantly (P < 0.01, P < 0.05). In comparison with the model group, the serum IL-4 contents in the SP 10 and ST 36 groups were decreased markedly (P < 0.05, P < 0.01), and serum IFN-gamma content and IFN-gamma/IL-4 in the ST 36 group were increased significantly (P < 0.05, P < 0.01). The IFN-gamma level was significantly higher in the ST 36 group than in the SP 10 group (P < 0.05). No significant differences were found between SP 10 and ST 36 groups in the spleen index, IL-4 and IFN-gamma/IL-4 (P > 0.05). CONCLUSION: Acupuncture at "Zusanli" (ST 36) can lengthen the time of forced swimming-induced exhaustion, and upregulate serum IFN-gamma content and IFN-gamma/IL-4 in exhausted swimming rats, which may contribute to its effect in correcting Th1/Th2 imbalance after strenuous exercise. The effect of acupuncture of ST 36 is superior to that of acupuncture of SP 10.