Secular trends in physical performance of Australian children. Evidence from the Talent Search program.

AIM: This study examined trends in aerobic fitness in 12-15-year-old South Australian schoolchildren in the years 1995-2000, based on data from the Australian Sports Commission's Talent Search program. METHODS: A total of 18,631 children were tested. The aerobic performance test used was the 20 m shuttle run test (20 mSRT). The 20 mSRT scores were expressed as completed laps, and converted to estimated VO(2)max values. RESULTS: There were significant declines (p=0.04-0.0001) across all age-gender slices, equivalent to 0.18 to 0.36 ml O(2) x kg(-1) x min(-1) x yr(-1), or about 0.4-0.8% of mean values per year. The rate of decline is consistent with several other Australian and overseas studies in the years 1980-2000, which have used a variety of aerobic tests across a wide range of age groups. In relation to children of similar age in 7 other countries, Australian children show poor to average aerobic fitness levels. CONCLUSION: It is possible that the decay in Australian children's aerobic fitness is in part due to reduced physical activity.

Identical twins are discordant for markers of eccentric exercise-induced muscle damage.

This study investigated whether the variability observed in the markers of exercise-induced muscle damage (EIMD) has a genetic etiology. Sixteen pairs of identical twins performed 24 maximal eccentric contractions (24MAX) using the elbow flexors. EIMD indicators were measured pre-24MAX and three days post-24MAX and included: post-exercise force deficit, maximal isometric force (ISO), plasma creatine kinase (CK), myoglobin (Mb), and joint range of motion. Force-time curves were recorded throughout the 24MAX. Twin siblings were alike for pre-exercise ISO (intraclass R = 0.89) and CK (R = 0.76) (p < 0.001), but were discordant for post-exercise force deficit (R = 0.29), CK (R = 0.15), and Mb (R = 0.17) (p > 0.05). In comparison with individuals minimally affected by the 24MAX, those who experienced the greatest force deficit 3 days post-exercise (> 50 %) were characterised by the greater application of eccentric force at longer muscle lengths (23.1 % vs 17.3 %) (p < 0.05). This study demonstrates that twins do not experience the same level of EIMD following identical exercise bouts. This suggests that the individual variability following high-force eccentric exercise cannot be attributed to genetic differences, refuting the idea that an inherited subclinical predisposition is responsible. From these results, a potential mechanism for the repeated bout effect is discussed.

Ultraendurance triathlon participation: typical race preparation of lower level triathletes.

BACKGROUND: This study sought to describe the training preparations and performances of lower level ultraendurance triatheletes. The lower level or typical ultraendurance athlete was defined as any participant eligible to compete, irrespective of ability. EXPERIMENTAL DESIGN: participants completed a retrospective questionnaire related to their athletic background, triathlon experience and performances, and training preparation. SETTING: all competitors in the 1995 Lanzarote Ironman (i.m.) triathlon had the opportunity to complete the questionnaire in the days prior to the race. PARTICIPANTS: 242 (230 m, 12 f) or 45% of the entire race field completed the questionnaire. MEASURES: measures of central tendency were used to describe all data. Forward step-wise multiple regression techniques were used to predict performance from training variables. Statistical significance was accepted at p < 0.05. RESULTS: Mean finish time for all study participants was 11.76 hours. Subjects were 34.2 +/- 8.8 years, 1.77 +/- 0.07 m, and 70.8 +/- 7.1 kg. They had 6.0 +/- 3.2 years experience in triathlon, had completed 3.0 +/- 4.1 IM races, and spent 21.5 +/- 10.8 weeks preparing for the IM. Training distances/week for swimming, cycling and running, were 8.8 +/- 4.3 km, 270 +/- 107 km, and 58.2 +/- 21.9 km, at a pace of 18.1 min/km, 31.8 km/hr, and 4.55 min/km respectively. Previous best performances in Olympic distance triathlon (1.5/40/10) coupled with weekly cycling distances and longest training ride, could partially predict overall performance (R2 = 0.57). CONCLUSIONS: Finishing an IM requires less training than has been previously reported in studies that have primarily focused on elite competitors. Additionally, training distances appear to be a more important factor for competitive success than training paces.

Evaluation of the Accusport Lactate Analyser.

An investigation of the Accusport Lactate Analyser (ACC) was undertaken to assess its accuracy, linearity, reliability, and versatility. Accuracy was determined by comparing 32 blood assays on the ACC with those obtained using the Kodak Ektachem E250 (E250). Linearity was determined over the range 1.2-18.7 mmol/L. Reliability was measured at 1.7 (low) and 14.4 (high) mmol/L concentrations. Versatility involved determining the optimal sample volume, influence of haematocrit, and the effect of time delay from sampling to assay. Assays determined using the ACC confirm good agreement with the E250. The difference between the two methods compared for lactate determination does not exceed 1.1 mmol/L for concentrations up to approximately 20 mmol/L. Linearity is demonstrated by the regression equation y = 0.026 + 0.970x, r = 0.995. Reliability is expressed by the coefficient of variation of 7% (low) and 4.6% (high). The optimal sample size for accurate assay was determined to be between 20 microL and 50 microL. Mean lactate value did not vary significantly between a haematocrit of 35% and 45%. The Accusport is accurate, linear up to at least 18.7 mmol/L, has good reliability at high and low concentrations, and is able to analyse whole blood up to 15 minutes after sample application to the reagent strip.

A physiological profile of elite surf ironmen, full time lifeguards & patrolling surf life savers.

The physiological profiles and proficiency of 32 volunteer surf life savers (LS), 15 professional lifeguards (LG), and 8 elite surf ironmen (IM) aged from 18 to 44 were compared. Measurements included anthropometry, muscular power, muscular strength-endurance, flexibility, VO2max, maximum heart rate, peak blood lactate response and proficiency in 3 rescue simulations. Both LG and IM were significantly faster than LS in all rescue simulations. IM had significantly greater VO2max (68.6 ml.kg-1.min-1) than LS (56.3) and LG (57.9). IM had significantly lower heart rates than LS after maximal swimming and running, and significantly lower blood lactate 3 minutes post swim (8.4 mmol/L) in comparison with LS (14.0) and LG (12.2). LG obtained better results than LS in 2 of the 3 muscular strength-endurance tasks. It is concluded that: LG and IM are significantly faster in aquatic rescue simulations than LS; IM have greater aerobic capacities than both other groups; the majority of Australian LS have adequate fitness and aquatic skills for surf rescue, although a small subset of LS do not. This group of poorly performing LS are not identified by current surf rescue screening procedures.