Serum electrolytes in Ironman triathletes with exercise-associated muscle cramping

PURPOSE: To compare serum electrolyte concentrations of cramping and control Ironman triathletes. METHODS: Triathletes suffering from acute exercise-associated muscle cramping (EAMC) after the 2000 South African Ironman Triathlon formed the cramping group (CR, N = 11). Non-cramping triathletes matched for race finishing time and body mass formed the control group (CON, N = 9). All subjects were weighed at race start and immediately post-race. Blood samples were drawn from both groups during recovery for the analysis of serum magnesium, glucose, sodium, potassium and chloride concentrations. Hemoglobin concentration and hematocrit were also measured. Surface electromyography (EMG) (mV) was recorded from a non-cramping control muscle (triceps) and the most severely cramping lower limb muscle of the CR group. EMG was recorded at the beginning of every minute for a 10-min period during recovery. RESULTS: There were no significant differences between the groups for body mass or percent body mass loss during the race. Post-race sodium concentration was significantly lower (P = 0.01) in the CR group than the CON group (140 +/- 2 vs 143 +/- 3 mmol.L) but was within the normal clinical range of post-race serum sodium concentrations. There were no significant differences between the two groups for post-race serum electrolytes, glucose, hemoglobin concentrations or hematocrit. Surface EMG (mV) was significantly higher (P < 0.05) in the cramping muscles than the control muscle of the CR group at 0, 3, 4, and 5 min of the 10-min recording period. CONCLUSION: Acute EAMC in ironman triathletes is not associated with a greater percent body mass loss or clinically significant differences in serum electrolyte concentrations. The increased EMG activity of cramping muscles may reflect increased neuromuscular activity.     

Ironman triathletes: MRI assessment of the shoulder

OBJECTIVE: The objective of this paper was to demonstrate the prevalence of shoulder magnetic resonance imaging (MRI) abnormalities, including abnormal bone marrow signal at the acromioclavicular (AC) joint in symptomatic and asymptomatic Ironman Triathletes. MATERIALS AND METHODS: The shoulders of 23 Ironman Triathletes, seven asymptomatic (group I) and 16 symptomatic (group II), were studied by MRI. A separate, non-triathlete group was evaluated specifically for AC joint marrow signal abnormalities to compare with the Ironman Triathletes. RESULTS: Partial thickness tears of the rotator cuff, rotator cuff tendinopathy, and AC joint arthrosis were common findings in both groups of triathletes. Tendinopathy was the only finding that was more prevalent in the symptomatic group, but this was not a statistically significant difference (p = 0.35). There were no tears of the glenoid labrum seen in group I or II subjects. Of note is that 71% (5/7) of group I subjects and 62% (10/16) of group II subjects had increased signal changes in the marrow of the AC joint (p = 0.68). The comparison group showed a lower prevalence (35%, p = 0.06) of this finding. CONCLUSIONS: No statistically significant difference was found among the findings for group 1, group 2, or the comparison group, although the difference between the comparison group and Ironman Triathletes approached statistical significance when evaluating for AC joint abnormal signal. Shoulder MRI of Ironman Triathletes should be interpreted with an appreciation of the commonly seen findings in asymptomatic subjects.     

Master triathletes have not reached limits in their Ironman triathlon performance

The purpose of this study was to analyze the participation and performance trends of male triathletes in the “Ironman Switzerland” from 1995 to 2010. Participation trends of all finishers aged between 18 and 64 years were analyzed over the 16‐year period by considering four 4‐year periods 1995–1998, 1999–2002, 2003–2006, and 2007–2010, respectively. The 3.8‐km swimming, 180‐km cycling, 42‐km running times, and total race times were analyzed for the top 10 triathletes in each age group from 18 to 64 years. The participation of master triathletes (≥40 years old) increased over the years, representing on average 23%, 28%, 37%, and 48% of total male finishers during the four 4‐year periods, respectively. Over the 1995–2010 period, triathletes older than 40 years significantly improved their performance in swimming, cycling, running, and in the total time taken to complete the race. The question whether master Ironman triathletes have yet reached limits in their performance during Ironman triathlon should be raised. Further studies investigating training regimes, competition experience, or socio‐demographic factors are needed to gain better insights into the phenomenon of the relative improvement in ultra‐endurance performance with advancing age.     

Upper body skinfold thickness is related to race performance in male Ironman triathletes

We investigated the association between skinfold thickness and race performance in male and female Ironman triathletes. Skinfold thicknesses at 8 sites and percent body fat were correlated to total race time including the split times for the 3 sub disciplines, for 27 male and 16 female Ironman athletes. In the males, percent body fat (r=0.76; p<0.0001), the sum of upper body skinfolds (r=0.75; p<0.0001) and the sum of all 8 skinfolds (r=0.71; p<0.0001) were related to total race time. Percent body fat (r=-0.67; p<0.001), the sum of upper body skinfolds (r=-0.63, p=0.0004) and the sum of all 8 skinfolds (r=-0.59; p<0.001) were also associated with speed in cycling during the race. In the females, none of the skinfold thicknesses showed an association with total race time, average weekly training volume or speed in the sub disciplines in the race. The results of this study indicate that low skinfold thicknesses of the upper body are related to race performance in male Ironman triathletes, but not in females.     

The effect of sex,age and performance level on pacing of Ironman triathletes

The aim of the present study was to examine the effect of sex, age and performance level on pacing of Ironman triathletes. Split times (i.e. swimming, cycling, and running) and overall race times of 343,345 athletes competing between 2002 and 2015 in 253 different Ironman triathlon races were analyzed. Participants were classified into nine performance groups according to their overall race time. Times in swimming, cycling, running and transition were expressed as percentage of the overall race time. Women spent relatively less time (%) in swimming, running and transition time, and more time (%) in cycling than men (p < 0.001). The fastest performance group was relatively faster in running (34.8 ± 1.4 versus 40.3 ± 3.0%, η²= 0.098) and transition time (0.9 ± 0.3 versus 2.2 ± 0.6%, η²= 0.178), and relatively slower in swimming (10.2 ± 0.8 versus 9.8 ± 1.5%, η²= 0.018) and cycling (54.1 ± 1.4 versus 47.8 ± 2.8%, η²= 0.138) than the slowest performance group (p < 0.001). The younger age groups were relatively faster in swimming, running and transition time, but relatively slower in cycling. In summary, the fastest Ironman triathletes were the relatively fastest in running and transition times. Thus, race tactics in an Ironman triathlon should focus on saving energy during swimming and cycling for the running split.     

Knees of Ironman triathletes: magnetic resonance imaging assessment of older (>35 years old) competitors

PURPOSE: To use magnetic resonance imaging (MRI) to evaluate the knees of older (>35 years old), competitive Ironman triathletes to determine the prevalence of abnormal findings. MATERIALS AND METHODS: The knees of 29 Ironman triathletes (20 men, 9 women; age range, 35-66 years old) were studied by MRI. The findings were analyzed collectively and categorized into group I (N = 13), subjects without prior knee injuries and symptoms, and group II (N = 16), subjects with prior knee injuries and/or current symptoms. RESULTS: Ten percent of the knees had ligamentous abnormalities, but the prevalence was not statistically different comparing group I to group II. Fifty-five percent had abnormal menisci. The overall prevalence of abnormal menisci was significantly higher in group II (69%) than in group I (38%, P < 0.05). Cartilage abnormalities were found in 21% of the triathletes with a higher prevalence in group II (31%) than in group I (8%, P < 0.05). Twenty-one percent (6/29) of the knees had bone contusions, with a higher prevalence in group II (31%) than in group I (8%, P < 0.05). CONCLUSION: In general, the spectrum of abnormal MRI findings of the knee was no greater than age-related changes previously reported for other athletic populations and nonathletes. These results have important implications for the diagnostic use of MRI of the knee in this high-endurance, athletic population.     

氧化应激与细胞凋亡

哺乳动物细胞的生存要求适当的氧化与抗氧化平衡，而活性氧中间产物则破坏这一平衡且在细胞凋亡中起重要作用。氧化应激介导的细胞凋亡，可能与活性氧中间产物对ＤＮＡ损伤导致的聚ＡＤＰ核糖转移酶活化和Ｐ５３的积累以及脂质过氧化物使细胞内Ｃａ＾２＋水平增加有关，氧化应激也可通过活化对其敏感的核转录因子如ＮＦ－ＫＢ诱导细胞凋亡。     

Oxidative stress in cardiovascular disease

The oxidative hypothesis of cardiovascular disease (CVD) has undergone tremendous changes during the past few years. Innumerable new proatherogenic effects have been added to the existing list that could be attributed to oxidative stress. However, both animal and human trials with a variety of antioxidants have failed to establish unambiguously a protective role for antioxidants in the prevention of CVD. This could be because of poor choice and dosage of antioxidants, incompatible experimental models, oxidative metabolism of the antioxidant, unrealistic expectations, and other reasons. More importantly, recent studies suggest that oxidative stress also could induce antioxidant enzymes in both cell culture and in vivo systems. In lieu of the potential of known deterrents of CVD such as exercise, estrogens, and the consumption of polyunsaturated fatty acids to induce an oxidative stress, the possibility that natural enhancement of antioxidant defense in the artery could better serve to deter CVD cannot be ignored. Thus, if oxidative stress does play a role in CVD, it may be better, in the absence of suitable animal models that respond to antioxidants, to adhere to behavioral and dietary changes that have been shown to benefit CVD.     

The effects of a high carbohydrate diet on cortisol and salivary immunoglobulin A (s-IgA) during a period of increase exercise workload amongst Olympic and Ironman triathletes

The present study observed the effects of a 6-day high carbohydrate (H-CHO) diet on salivary cortisol and IgA during a period of increased exercise workload. Thirty-two competitively trained male triathletes were randomly allocated into a self-selected (SS), or an H-CHO (12 g CHO kgbm (-1) . day (-1)) dietary group. In addition to their training regimes, all subjects performed a 1-hour running exercise bout at 70 % V.O (2max) . d (-1), for six days. Saliva samples were taken pre, immediately post, and morning post-exercise bout on days 1, 4, and 6. The concentrations of s-IgA and cortisol were determined by ELISA assays. There was a significant (p < 0.001) interaction between Group x Time for cortisol, with a marked increase in concentrations occurring in the SS dietary group pre to post exercise, and pre to morning post-exercise (p < 0.01). Conversely, a significant (p = 0.009) Group x Time interaction reflected higher post exercise s-IgA concentrations (p < 0.005) than pre exercise in the H-CHO diet group. Blood glucose concentration decreased pre to post exercise in the SS diet group (p < 0.01), whilst remaining stable in the H-CHO group. It is concluded that the consumption of a high CHO diet throughout a 6-day period of overtraining had a favourable effect on markers of immune activity and thereby reduced the susceptibility of these endurance athletes to upper respiratory tract infection URTI.     

Ultraviolet exposure in the Ironman triathlon

PURPOSE: Skin cancer is increasing worldwide and exposure to ultraviolet (UV) radiation is thought to be the most important environmental risk factor. People practicing outdoor sports are exposed to considerable amounts of UV radiation from the sun. METHODS: Three triathletes participated in the Ironman Triathlon World Championships 1999 in Hawaii (3.9-km swim, 180.2-km bike, 42.4-km run). They attached Bacillus subtilis spore film dosimeters (VioSpor) on the back between their shoulders. The dosimeter system measured cumulative biologically weighted erythemal UV exposure. UV exposure is given in minimal erythema doses (1 MED corresponds to 250 J x m(-2) at 298 nm). RESULTS: The mean personal UV exposure was 8.3 MED (6.9--9.7 MED) after 8:43 to 9:44 h of competition corresponding to 0.8 to 1.3 MED x h(-1) (bike and run). The athletes were sunburned despite the use of water-resistant sunscreen (SPF 25+) on sun exposed skin. CONCLUSION: The International Radiation Protection Agency has issued guidelines for professional UV exposure. Ironman triathletes considerably exceeded these limits of exposure similar to other outdoor sports. Professional and amateur athletes should be aware of hazards caused by UV radiation. Adequate protection by water-resistant sunscreens and clothing as well as training and competition schedules with low sun exposure seem to be a reasonable recommendation.     

Hyponatremia in ultradistance triathletes.

PURPOSE: Hyponatremia ([plasma sodium] <135 mmol x L(-1)) is a potentially serious complication of ultraendurance sports. However, the etiology of this condition is still uncertain. This observational cohort study aimed to determine prospectively the incidence and etiology of hyponatremia in an ultradistance triathlon. METHODS: The subjects consisted of 605 of the 660 athletes entered in the New Zealand Ironman triathlon (3.8-km swim, 180-km cycle, and 42.2-km run). Subjects were weighed before and after the race. A blood sample was drawn for measurement of plasma sodium concentration after the race. RESULTS: Complete data on pre- and postrace weights and plasma sodium concentrations were available in 330 race finishers. Postrace plasma sodium concentrations were inversely related to changes in body weight (P = 0.0001). Women (N = 38) had significantly lower plasma sodium concentrations (133.7 vs 137.4 mmol x L(-1); P = 0.0001) than men (N = 292) and lost significantly less relative weight (-2.7 vs -4.3%; P = 0.0002). Fifty-eight of 330 race finishers (18%) were hyponatremic; of these only 18 (31%) sought medical care for the symptoms of hyponatremia (symptomatic). Eleven of the 58 hyponatremic athletes had severe hyponatremia ([plasma sodium] < 130 mmol x L(-1)); seven of these 11 severely hyponatremic athletes were symptomatic. The relative body weight change of the 11 severely hyponatremic athletes ranged from 2.4% to +5%; eight (73%) of these athletes either maintained or gained weight during the race. In contrast, relative body weight changes in the 47 athletes with mild hyponatremia ([plasma sodium] 130-134 mmol x L(1)) were more variable, ranging from -9.25% to +2.2%. CONCLUSIONS: Hyponatremia is a common biochemical finding in ultradistance triathletes but is usually asymptomatic. Although mild hyponatremia was associated with variable body weight changes, fluid overload was the cause of most (73%) cases of severe, symptomatic hyponatremia.     

Overuse injuries in ultraendurance triathletes

Overuse injuries represent the largest percentage of sports-related injuries requiring medical treatment. These injuries represent a substantial health issue for the millions of adults who have made physical activity an integral part of their lifestyle, but may be even more important to those pursuing ultraendurance exercise. The purposes of this study were to report the type and incidence of overuse injuries in ultraendurance triathletes and to relate training practices to injury occurrence. Data was gathered from the responses of 95 competitors (75 men, 20 women) in the 1986 Hawaii Ironman Triathlon who completed a training and medical history questionnaire. In this sample, virtually all (91%) sustained at least one soft tissue, overuse injury during the previous year's training. The area of the body most frequently involved was the back, but the most common pattern was to have multiple areas involved. Because of the consistent combinations of injuries, mechanical abnormalities, such as diminished shock absorption, may have contributed to injury. Training habits were extremely variable and not directly related to either the incidence or type of injury.     

Training patterns and sports injuries in triathletes

Sports-related injuries are a significant health problem within Australia, and constitute a national health priority. There is limited Australian research data available on factors that contribute to triathlon injuries, and in particular on how training patterns relate to injury risk. This study examined the association between training patterns and injury in mostly non-elite triathletes. A cross-sectional survey of 258 triathletes completed a questionnaire that focused on injuries they had sustained during the previous three triathlon seasons. Statistical associations were found between hours of training and sustaining an injury. These associations were U shaped, with those triathletes training at low levels and at high levels more likely to sustain an injury. The results suggest that, for non-elite triathletes, the likelihood of sustaining an injury is least when training for a total of 8 to 10 hrs per week, specifically cycling for five to six hrs and running for three to four hrs weekly. Time spent on swimming training does not appear to affect injury risk. This research is seen as a contribution towards assisting triathletes in the planning of training programs aimed at reducing the risk of injury.     

氧化应激与帕金森病多巴胺神经元死亡

目前,帕金森病的病因不十分清楚,为了更好地理解其病理过程,提出了各种神经变性的机制,包括自由基生成、氧化应激、线粒体异常、兴奋性中毒、钙中毒、营养因子不足、炎症过程、一氧化氮（NO）毒性和细胞调亡。这些因素相互增强形成恶性循环,导致神经功能异常、萎缩,最终导致多巴胺神经细胞死亡（图1）。     

Oxidative stress : relationship with exercise and training

Free radicals are reactive compounds that are naturally produced in the human body. They can exert positive effects (e.g. on the immune system) or negative effects (e.g. lipids, proteins or DNA oxidation). To limit these harmful effects, an organism requires complex protection - the antioxidant system. This system consists of antioxidant enzymes (catalase, glutathione peroxidase, superoxide dismutase) and non-enzymatic antioxidants (e.g. vitamin E [tocopherol], vitamin A [retinol], vitamin C [ascorbic acid], glutathione and uric acid). An imbalance between free radical production and antioxidant defence leads to an oxidative stress state, which may be involved in aging processes and even in some pathology (e.g. cancer and Parkinson's disease). Physical exercise also increases oxidative stress and causes disruptions of the homeostasis. Training can have positive or negative effects on oxidative stress depending on training load, training specificity and the basal level of training. Moreover, oxidative stress seems to be involved in muscular fatigue and may lead to overtraining.