Physical Demands of Elite Women's Ultimate Frisbee Between Halves and Across Matches in an International Tournament.

ABSTRACT: Palmer, JA, Landers, G, Buttfield, A, and Polglaze, T. Physical demands of elite women's Ultimate Frisbee between halves and across matches in an international tournament. J Strength Cond Res 36(3): 838-844, 2022-To quantify the physical match demands of elite women's Ultimate Frisbee across a tournament, elite female Ultimate players (N = 9) from the Australian Under 24 Women's team wore global positioning system units in all 12 matches of the 2018 Under 24 World Championship competition. Temporal, displacement, and energetic parameters were obtained. Distribution of activity above and below a generic speed threshold (12.42 km·h-1) and its equivalent metabolic power value (16.02 W·kg-1) were determined. Players spent 12:44 ± 6:41 min:s on the field, covered 1,559 ± 741 m and expended 8.95 ± 4.21 kJ·kg-1 during a match. The mean stint duration was 2:00 ± 0:48 min:s, mean bench duration was 13:25 ± 7:05 min:s, and work-to-recovery ratio was 0.22 ± 0.11. Players performed 57 ± 27 high-speed runs per match and 45 ± 20 high-accelerations. Mean match speed was 127 ± 18 m·min-1, mean metabolic power was 12.2 ± 1.7 W·kg-1, and mean intermittency index was 1.24 ± 0.04. No differences were found between halves for any parameters. Compared with the first 4 matches, the last 4 matches were shorter and more intense (p < 0.05). At the international level, Ultimate is an intense and highly intermittent sport, characterized by brief playing stints interspersed with long periods of recovery, which allow playing intensity to be maintained throughout a match and elevated in the latter stages of a tournament. The information gained from this research can be used to guide the creation of Ultimate-specific conditioning programs for elite female players.

A Combination of Ice Ingestion and Head Cooling Enhances Cognitive Performance during Endurance Exercise in the Heat.

This study assessed the effectiveness of head cooling during exercise in the heat on cognitive performance, either alone or with ice ingestion. Ten healthy males, non-acclimatized to heat, ran (70% V̇O2peak) for 2×30 min in heat (35 ± 0.9°C, 68.2 ± 6.9% RH). Participants completed 3 trials: 10 min of head cooling during exercise (HC); precooling with crushed ice (7gikg-1) and head cooling during exercise (MIX); or no-cooling/control (CON). Working memory was assessed using the automated operation span task (OSPAN) and serial seven test (S7). Following MIX, S7 scores were improved compared to CON (12 ± 9.5, p = 0.004, d = 1.42, 0.34-2.28) and HC (4 ± 5.5, p = 0.048, d = 0.45, -0.47 to 1.3) during exercise. Moderate to large effect sizes were recorded for S7 and OSPAN following MIX and HC compared to CON, suggesting a tendency for improved cognitive performance during exercise in heat. Following precooling (MIX), core body temperature (Tc) and forehead temperature (Th) were lower compared to baseline (-0.75 ± 0.37°C, p < 0.001; -0.31 ± 0.29°C, p = 0.008, respectively) but not in HC or CON (p > 0.05). Thermal sensation (TS) was lower in MIX and HC compared to CON during exercise (p < 0.05). The reduction in Tc, Th and TS with MIX may have attenuated the effect of heat and subsequently improved working memory during exercise in heat.

Ice Ingestion Maintains Cognitive Performance during a Repeated Sprint Performance in The Heat.

This study investigated the effects of precooling via crushed ice ingestion on cognitive performance during repeated-sprint cycling in the heat. Nine males, non-heat acclimatised to heat (mean age: 28.2 ± 2.7 y; height: 175.7 ± 9.7 cm; body-mass: 76.9 ± 10.6 kg) completed a 30 min bout of repeated-sprint (36 × 4 s sprints, interspersed with 56 s rest-breaks) on a cycle ergometer in a climate chamber (35°C, 70% relative humidity). Crushed ice ingestion (7g·kg-1, -0.4°C, ICE) or no cooling (CON) interventions were completed at rest, in the climate chamber, 30 min prior to exercise. Working memory was assessed via the serial seven test (S7) and the automated operation span task (OSPAN) at various time points before, during, and post-exercise. Core body temperature (Tc), forehead temperature (Th), and thermal sensation (TS) were assessed throughout the protocol. Working memory significantly declined during exercise in CON as measured by S7 (p = 0.01) and OSPAN (p = 0.03); however, it was preserved in ICE with no change at the end of exercise in either S7 or OSPAN scores compared to baseline (p = 0.50, p = 0.09, respectively). Following precooling, Th (-0.59°C, p < 0.001) and Tc (-0.67°C, p = 0.005) were significantly decreased in ICE compared to CON. At the end of the exercise, ICE significantly reduced Tc compared to CON (p = 0.03), but no significant differences were recorded for Th. Further, TS was lower following precooling in ICE (p = 0.008) but not during exercise. In conclusion, ice ingestion significantly reduced Th and Tc and facilitated maintenance of cognitive performance during repeated-sprint exercise in the heat, which may lead to better decision making.

Strength Training in Long-Distance Triathletes: Barriers and Characteristics.

ABSTRACT: Luckin, KM, Badenhorst, CE, Cripps, AJ, Landers, GJ, Merrells, RJ, Bulsara, MK, and Hoyne, GF. Strength training in long-distance triathletes: Barriers and characteristics. J Strength Cond Res 35(2): 495-502, 2021-The purpose of this investigation was to identify perceived and physical barriers toward the completion of concurrent strength training and endurance training in long-distance triathletes. Three hundred ninety long-distance triathletes (224 women, 166 men; age [y]: 39 ± 10) completed a 68-question self-administered, semiquantitative survey that assessed endurance and strength training characteristics, experience in triathlon, and perceived barriers regarding the completion of strength training. Mean training hours per week was 14.92 ± 5.25, with 54.6% reporting participation in strength training. Heavy strength training was the most commonly reported (39.4%), with significantly more men completing this form of strength training (p < 0.001). Results from subjects who did not complete strength training indicated that perceived time constraints (53.1%) in addition to lack of knowledge on exercise progression and form (52.5%) are prominent perceived barriers to strength training completion. Identification of the barriers perceived by long-distance triathletes that prevent them from completing concurrent strength training and endurance training may be useful for coaches, athletes, and sports scientists who seek to incorporate strength training for injury prevention and performance improvement.

Influence of Electronic Devices on Sleep and Cognitive Performance During Athlete Training Camps.

ABSTRACT: Jones, MJ, Dawson, B, Eastwood, PR, Halson, SL, Miller, J, Murray, K, Dunican, IC, Landers, GJ, and Peeling, P. Influence of electronic devices on sleep and cognitive performance during athlete training camps. J Strength Cond Res 35(6): 1620-1627, 2021-This study investigated the effects of removing athletes' electronic devices in the evening on sleep and performance during training camps. Water polo athletes (n = 26) attending a 7-night training camp (study 1) and triathletes (n = 23) attending a 4-night training camp (study 2) were randomly allocated to a no-device group (no electronic devices could be used after dinner or overnight; ND) or control group (unrestricted electronic device use; CON). Sleep was monitored through wrist actigraphy. The ND group completed a questionnaire measuring anxiety related to being unable to use electronic devices ("nomophobia"). Triathletes also completed a psychomotor vigilance test (PVT) at the start and end of camp. Water polo ND athletes went to bed earlier and spent longer time in bed than CON on the first night, but not on other nights. In triathletes, sleep quantity was not different between groups on any night. No statistically significant differences were observed for changes in nomophobia from the first to the last night of camp. No differences in PVT performance were observed between ND and CON triathletes. In conclusion, removal of evening electronic devices does not improve sleep quantity or cognitive performance in athletes during short-duration (4-7 nights) training camps.

Head Cooling Prior to Exercise in the Heat Does Not Improve Cognitive Performance.

This study investigated the effectiveness of head cooling on cognitive performance after 30 min and 60 min of running in the heat. Ten moderately-trained, non-heat-acclimated, male endurance athletes (mean age: 22 ± 6.6 y; height: 1.78 ± 0.10 m; body-mass: 75.7 ± 15.6 kg; VO2peak: 51.6 ± 4.31 mL-1>kg-1>min) volunteered for this study. Participants performed two experimental trials: head cooling versus no-cooling (within-subjects factor with trial order randomized). For each trial, participants wore a head-cooling cap for 15 min with the cap either cooled to 0°C (HC) or not cooled (22°C; CON). Participants then completed 2 × 30 min running efforts on a treadmill at 70% VO2peak in hot conditions (35°C, 70% relative humidity), with a 10 min rest between efforts. Working memory was assessed using an operation span (OSPAN) task immediately prior to the 15 min cooling/no-cooling period (22°C, 35% RH) and again after 30 min and 60 min of running in the heat. Numerous physiological variables, including gastrointestinal core temperature (Tc) were assessed over the protocol. Scores for OSPAN were similar between trials, with no interaction effect or main effects for time and trial found (p = 0.58, p = 0.67, p = 0.54, respectively). Forehead temperature following precooling was lower in HC (32.4 ± 1.6°C) compared with CON (34.5 ± 1.1°C) (p = 0.01), however, no differences were seen in Tc, skin temperature, heart rate and ratings of perceived exertion between HC and CON trials at any time point assessed (p > 0.05). In conclusion, despite HC reducing forehead temperature prior to exercise, it did not significantly improve cognitive performance during (half-time break) or after subsequent exercise in hot environmental conditions, compared to a no cooling control.

Physical and perceptual cooling: Improving cognitive function, mood disturbance and time to fatigue in the heat.

This study investigated the effects of menthol swilling and crushed ice ingestion on cognitive function, total mood disturbance (TMD), and time to fatigue (TTF). Twelve male long-distance runners completed three counterbalanced running trials (3 × 30 minutes at 65% VO2peak and a TTF run at 100% VO2peak ) in hot, humid conditions (35.3 ± 0.3°C, 59.2 ± 2.5% relative humidity). Trials consisted of precooling with crushed ice ingestion and mid-cooling by menthol swilling (MIX), precooling with water ingestion and mid-cooling by menthol swilling (MENTH), and control (CON). Swilling with either 25 mL of menthol solution or placebo occurred upon entry to the heat, at 15-minute intervals during the run and prior to the TTF run. Core temperature, forehead skin temperature, tympanic temperature, perceived thermal sensation, and TMD were significantly lower with MIX compared with MENTH and CON (P < .05). Thirst was satiated in MIX compared with CON; however, MENTH did not have a significant effect. After 90 minutes of running and post-TTF run, fewer errors occurred in the executive control task (P < .05), as well as decision-making and working memory (P > .05; d = 0.5-0.79) between MIX and CON; however, MENTH had no effect compared with CON. The TTF run was significantly longer with MENTH (34.38%; P = .02) and MIX (39.06%; P = .001) compared with CON, with no difference between MENTH and MIX (P = .618). The physical reduction in core and internal head temperature seen with crushed ice ingestion may lead to improvements in cognitive function; however, both MENTH and MIX were sufficient for improving exercise performance.

Comparison of Linear and Reverse Linear Periodized Programs With Equated Volume and Intensity for Endurance Running Performance.

Bradbury, DG, Landers, GJ, Benjanuvatra, N, and Goods, PS. Comparison of linear and reverse linear periodized programs with equated volume and intensity for endurance running performance. J Strength Cond Res 34(5): 1345-1353, 2020-This investigation examined the effectiveness of 2 periodization methods on endurance running performance. Thirty recreational runners (25.2 ± 7.4 years; 175.4 ± 8.1 cm; 69.0 ± 9.8 kg) were assigned to 3 groups based on preintervention test results: linear periodization group (LPG, n = 10), reverse linear periodization group (RPG, n = 10), and control group (CG, n = 10). The LPG and RPG completed 3 training sessions (2 supervised and 1 unsupervised) per week in two 6-week blocks. The LPG went through a high-volume training program while the RPG performed higher intensity, lower volume training in the initial block. Training volume and intensity was reversed in the second 6-week training block. All subjects completed pre-training (week 0), midpoint (week 7), and post-training (week 14) testing, which included anthropometric measurements (body mass and sum of 8 skinfolds), treadmill tests for running economy (RE) and V[Combining Dot Above]O2max, and a 5,000-m time trial (TT) on a 400-m grass track. Greater improvements in the 5,000-m TT were observed in the LPG (76.8 ± 55.8 seconds, p = 0.009, d = 1.27) and the RPG (112.8 ± 83.4 seconds, p = 0.002, d = 1.51) than the CG (3.6 ± 59 seconds). No significant differences were found between the LPG and RPG (p = 0.321, d = 0.51). No group differences were found for V[Combining Dot Above]O2peak (p = 0.955) or RE at 9 km·h (p = 0.329) or 11 km·h (p = 0.558), respectively. However, significant improvements were seen in these variables after training: V[Combining Dot Above]O2peak (p = 0.010), RE 9 km·h (p < 0.001), and RE 11 km·h (p = 0.004). These results do not support linear periodization or reverse linear periodization as a superior method; however, periodized training elicited greater improvements in endurance performance than nonperiodized training, highlighting the importance of planned training structure.

Internal precooling decreases forehead and core temperature but does not alter choice reaction time during steady state exercise in hot, humid conditions.

This study aimed to determine if precooling via crushed ice ingestion reduces forehead skin temperature (Thead) and core temperature (Tcore) during exercise in the heat and whether it has an effect on choice reaction time (CRT). Ten males commenced a 30 min precooling period, ingesting either 7 g kg-1 of crushed ice (ICE) or room temperature water (CON) prior to cycling 60 min at 55% V̇O2peak in hot, humid conditions (35.0 ± 0.3 °C, 50.2 ± 2.1% Relative Humidity). The CRT task was completed upon arrival and after the precooling period in the lab, then at 15 min intervals during exercise in the heat. Precooling reduced Thead and Tcore to a greater degree in ICE (Thead: -0.8 ± 0.31 °C; Tcore: -0.9 ± 0.3 °C) compared with CON (Thead: -0.2 ± 0.3 °C; Tcore: -0.2 ± 0.2 °C) (p ≤ 0.001). Choice reaction time performance improved throughout the cycle for both conditions (p ≤ 0.05). Ice ingestion lowered thermal sensation (p = 0.003) and skin temperature (d = 0.88; Tskin), while heart rate, ratings of perceived exertion and thirst were similar between conditions (p > 0.05). Precooling effectively reduced Thead and Tcore but did not provide additional improvement in CRT during moderate exercise in the heat. Further investigation is required to determine whether the lower central and peripheral temperature after ice ingestion is beneficial for tasks of greater cognitive effort.

Interleukin-6 and Hepcidin Levels during Hormone-Deplete and Hormone-Replete Phases of an Oral Contraceptive Cycle: A Pilot Study.

BACKGROUND: In the past, elevated estradiol levels were reported to downregulate the iron regulatory hormone hepcidin, thereby potentially improving iron metabolism. As estrogen plays a role in regulating the menstrual cycle and can influence the cytokine interleukin-6 (IL-6; a hepcidin up-regulator), this investigation examined the effects of estradiol supplementation achieved by the use of a monophasic oral contraceptive pill (OCP) on IL-6, hepcidin levels and iron status during the hormone-deplete versus hormone-replete phases within an oral contraceptive cycle (OCC). METHODS: Fifteen healthy female OCP users were recruited and provided a venous blood sample on 2 separate mornings during a 28-day period. These included (a) days 2-4 of the OCC, representing a hormone-free withdrawal period (WD); (b) days 12-14 of the OCC, representing the end of the first week of active hormone therapy (AHT). RESULTS: IL-6 and hepcidin levels were not significantly different at WD and AHT. Serum ferritin was significantly higher (p = 0.039) during AHT as compared to WD. CONCLUSIONS: Fluctuations in OCP hormones (estradiol and/or progestogen) had no effect on basal IL-6 and hepcidin levels in young women. Nevertheless, elevated ferritin levels recorded during AHT may indicate that OCP hormones can positively influence iron stores within an OCC despite unchanged hepcidin levels.

Crushed Ice Ingestion Does Not Improve Female Cycling Time Trial Performance in the Heat.

This study examined the effects of precooling via ice ingestion on female cycling performance in hot, humid conditions. Ten female endurance athletes, mean age (28 ± 6 y), height (167.6 ± 6.5 cm) and body-mass (68.0 ± 11.5 kg) participated in the study. Participants completed an 800 kJ cycle time-trial in hot, humid conditions (34.9 ± 0.3 °C, 49.8 ± 3.5% RH). This was preceded by the consumption of 7 g∙kg-1 of crushed ice (ICE) or water (CON). There was no difference in performance time (CON 3851 ± 449 s; ICE 3767 ± 465 s), oxygen consumption (CON 41.6 ± 7.0 ml∙kg∙min-1; ICE 42.4 ± 6.0 ml∙kg∙min-1) or respiratory exchange ratio (CON 0.88 ± 0.05; ICE 0.90 ± 0.06) between conditions (p > .05, d < 0.5). Core and skin temperature following the precooling period were lower in ICE (Tc 36.4 ± 0.4 °C; Tsk 31.6 ± 1.2 °C) compared with CON (Tc 37.1 ± 0.4 °C; Tsk 32.4 ± 0.7 °C) and remained lower until the 100 kJ mark of the cycle time-trial (p < .05, d > 1.0). Sweat onset occurred earlier in CON (228 ± 113 s) compared with ICE (411 ± 156 s) (p < .05, d = 1.63). Mean thermal sensation (CON 1.8 ± 2.0; ICE 1.2 ± 2.5, p < .05, d = 2.51), perceived exertion (CON 15.3 ± 2.9; ICE 14.9 ± 3.0, p < .05, d = 0.38) and perceived thirst (CON 5.6 ± 2.2; ICE 4.6 ± 2.4, p < .05, d = 0.98) were lower in ICE compared with CON. Crushed ice ingestion did not improve cycling performance in females, although perceptual responses were reduced.

The Effects of Crushed Ice Ingestion Prior to Steady State Exercise in the Heat.

This study examined the physiological effects of crushed ice ingestion before steady state exercise in the heat. Ten healthy males with age (23 ± 3 y), height (176.9 ± 8.7 cm), body-mass (73.5 ± 8.0 kg), VO2peak (48.5 ± 3.6 mL∙kg∙min-1) participated in the study. Participants completed 60 min of cycling at 55% of their VO2peak preceded by 30 min of precooling whereby 7 g∙kg-1 of thermoneutral water (CON) or crushed ice (ICE) was ingested. The reduction in Tc at the conclusion of precooling was greater in ICE (-0.9 ± 0.3 °C) compared with CON (-0.2 ± 0.2 °C) (p ≤ .05). Heat storage capacity was greater in ICE compared with CON after precooling (ICE -29.3 ± 4.8 W∙m-2; CON -11.1 ± 7.3 W∙m-2, p < .05). Total heat storage was greater in ICE compared with CON at the end of the steady state cycle (ICE 62.0 ± 12.5 W∙m-2; CON 49.9 ± 13.4 W∙m-2, p < .05). Gross efficiency was higher in ICE compared with CON throughout the steady state cycle (ICE 21.4 ± 1.8%; CON 20.4 ± 1.9%, p < .05). Ice ingestion resulted in a lower thermal sensation at the end of precooling and a lower sweat rate during the initial stages of cycling (p < .05). Sweat loss, respiratory exchange ratio, heart rate and ratings of perceived exertion and thirst were similar between conditions (p > .05). Precooling with crushed ice led to improved gross efficiency while cycling due to an increased heat storage capacity, which was the result of a lower core temperature.

Caffeine Ingestion Improves Repeated Freestyle Sprints in Elite Male Swimmers.

The purpose of this investigation was to determine the efficacy of a moderate dose of caffeine to improve repeat-sprint performance in elite freestyle sprinters. Nine highly trained male swimmers performed 6 x 75 m freestyle sprints on two occasions 1-h after consuming either 3 mg·kg-1 caffeine (CAF), or placebo, in a cross-over manner. Capillary blood samples for the analysis of blood lactate concentration and pH were collected after the 1st, 3rd, and 5th sprint, while heart rate and perceived exertion (RPE) were collected after every sprint. There was a moderate effect for improved mean sprint time in the CAF condition (0.52 s; 1.3%; d = 0.50). When assessed individually, there was a large effect for improved performance in sprints 3 (1.00 s; 2.5%; d = 1.02) and 4 (0.84 s; 2.1%; d = 0.84) in CAF compared to placebo, with worthwhile performance improvement found for each of the first 5 sprints. There was a significant treatment effect for higher blood lactate concentration for CAF (p = 0.029), and a significant treatment*time effect for reduced pH in the CAF condition (p = 0.004). Mean heart rate (167 ± 9 bpm vs 169 ± 7 bpm) and RPE (17 ± 1 vs 17 ± 1) were not different between placebo and CAF trials, respectively. This investigation is the first to demonstrate enhanced repeat-sprint ability in swimmers following acute caffeine ingestion. It appears likely that the combination of a moderate dose of caffeine (3-6 mg·kg-1) with trained athletes is most likely to enhance repeat-sprint ability in various athletic populations; however, the exact mechanism(s) for an improved repeat-sprint ability following acute caffeine ingestion remain unknown.

No Additional Benefit of Repeat-Sprint Training in Hypoxia than in Normoxia on Sea-Level Repeat-Sprint Ability.

To assess the impact of 'top-up' normoxic or hypoxic repeat-sprint training on sea-level repeat-sprint ability, thirty team sport athletes were randomly split into three groups, which were matched in running repeat-sprint ability (RSA), cycling RSA and 20 m shuttle run performance. Two groups then performed 15 maximal cycling repeat-sprint training sessions over 5 weeks, in either normoxia (NORM) or hypoxia (HYP), while a third group acted as a control (CON). In the post-training cycling RSA test, both NORM (13.6%; p = 0.0001, and 8.6%; p = 0.001) and HYP (10.3%; p = 0.007, and 4.7%; p = 0.046) significantly improved overall mean and peak power output, respectively, whereas CON did not change (1.4%; p = 0.528, and -1.1%; p = 0.571, respectively); with only NORM demonstrating a moderate effect for improved mean and peak power output compared to CON. Running RSA demonstrated no significant between group differences; however, the mean sprint times improved significantly from pre- to post-training for CON (1.1%), NORM (1.8%), and HYP (2.3%). Finally, there were no group differences in 20 m shuttle run performance. In conclusion, 'top-up' training improved performance in a task-specific activity (i.e. cycling); however, there was no additional benefit of conducting this 'top-up' training in hypoxia, since cycle RSA improved similarly in both HYP and NORM conditions. Regardless, the 'top-up' training had no significant impact on running RSA, therefore the use of cycle repeat-sprint training should be discouraged for team sport athletes due to limitations in specificity. Key points'Top-up' repeat-sprint training performed on a cycle ergometer enhances cycle repeat-sprint ability compared to team sport training only in football players.The addition of moderate hypoxia to repeat-sprint training provides no additional performance benefits to sea-level repeat-sprint ability or endurance performance than normoxic repeat-sprint training.'Top-up' cycling repeat-sprint training provides no significant additional benefit to running RSA or endurance performance than team sport training only, and therefore running based repeat-sprint interventions are recommended for team sport athletes.

Sand training: a review of current research and practical applications.

Sand surfaces can offer a higher energy cost (EC) and lower impact training stimulus compared with firmer and more traditional team sport training venues such as grass. This review aims to summarise the existing research on sand training, with a specific focus on its application as a team sports training venue. Compared with grass, significant physiological and biomechanical differences are associated with sand exercise. However, evidence also exists to suggest that training adaptations unique to sand can positively influence firm-ground performance. Furthermore, the lower impact forces experienced on sand can limit muscle damage, muscle soreness, and decrements in performance capacity relative to exercise intensity. Therefore, using a sand training surface in team sports may allow greater training adaptations to be achieved, while reducing performance decrements and injuries that may arise from heavy training. Nevertheless, further research should investigate the effect of sand surfaces over a greater range of training types and performance outcomes, to increase the application of sand training for team sports.

Effect of sand versus grass training surfaces during an 8-week pre-season conditioning programme in team sport athletes.

This study compared the use of sand and grass training surfaces throughout an 8-week conditioning programme in well-trained female team sport athletes (n = 24). Performance testing was conducted pre- and post-training and included measures of leg strength and balance, vertical jump, agility, 20 m speed, repeat speed (8 × 20 m every 20 s), as well as running economy and maximal oxygen consumption (VO2max). Heart rate (HR), training load (rating of perceived exertion (RPE) × duration), movement patterns and perceptual measures were monitored throughout each training session. Participants completed 2 × 1 h conditioning sessions per week on sand (SAND) or grass (GRASS) surfaces, incorporating interval training, sprint and agility drills, and small-sided games. Results showed a significantly higher (P < 0.05) HR and training load in the SAND versus GRASS group throughout each week of training, plus some moderate effect sizes to suggest lower perceptual ratings of soreness and fatigue on SAND. Significantly greater (P < 0.05) improvements in VO2max were measured for SAND compared to GRASS. These results suggest that substituting sand for grass training surfaces throughout an 8-week conditioning programme can significantly increase the relative exercise intensity and training load, subsequently leading to superior improvements in aerobic fitness.

Iron regulation in athletes: exploring the menstrual cycle and effects of different exercise modalities on hepcidin production.

The trace element iron plays a number of crucial physiological roles within the body. Despite its importance, iron deficiency remains a common problem among athletes. As an individual's iron stores become depleted, it can affect their well-being and athletic capacity. Recently, altered iron metabolism in athletes has been attributed to postexercise increases in the iron regulatory hormone hepcidin, which has been reported to be upregulated by exercise-induced increases in the inflammatory cytokine interleukin-6. As such, when hepcidin levels are elevated, iron absorption and recycling may be compromised. To date, however, most studies have explored the acute postexercise hepcidin response, with limited research seeking to minimize/attenuate these increases. This review summarizes the current knowledge regarding the postexercise hepcidin response under a variety of exercise scenarios and highlights potential areas for future research-such as: a) the use of hormones though the female oral contraceptive pill to manipulate the postexercise hepcidin response, b) comparing the use of different exercise modes (e.g., cycling vs. running) on hepcidin regulation.

Symptoms of heat illness and water consumption habits in mine industry workers over the summer months in Australia.

Mine industry workers (n=515) from various locations in Australia completed a questionnaire to assess the prevalence of symptoms associated with heat-related illness and water consumption habits during a summer season. Participants read from a pre-defined list and noted any heat-related symptoms that they had experienced. The most prevalent symptoms experienced were fatigue, headache, sweating, and dark coloured urine, with 77% of respondents reporting at least one symptom. Workers with shorter employment durations had higher rates of reporting multiple symptoms (rates ratios: 1.40-1.72). The most prevalent water consumption amounts over an 11-12 h shift were 2-4 L by 37.3% of total respondents, followed by 1-2 L by 36.5% of respondents. Employers should inform workers about the severe implications of heat-related illnesses, implement regular water breaks, and educate personnel about the importance of water intake. Providing employees with self-check methods of hydration status is recommended to increase awareness of their hydration status.

Heat exposure as a cause of injury and illness in mine industry workers.

The objective of this study was to explore the association between ambient temperature and injuries and illnesses experienced by mine industry workers. Eleven years of de-identified data from a mine industry company in Australia was explored in regards to injuries and illnesses occurring due to outdoor exposure. Each case was filtered for reported symptoms, and meteorological data to match the location of the mine site and date reported were sourced. Of the 18 931 injuries and illnesses observed over the 11-year period, 151 cases of heat-related illness due to outdoor exposure were reported. Twenty-five conditions/symptoms of heat-illness were found, with the most prevalent being dehydration (n = 81), followed by heat rash (n = 40), dizziness (n = 24), and headache (n = 23). The mean number of symptoms reported by each worker was 2 ± 1. There was a positive correlation between ambient temperature and injuries/illnesses (r2 = 0.89, P < 0.001), where, as temperature increased so did the number of reported heat-related illnesses. Underreporting of heat-related illness and injury in the mining industry is likely, which is a risk to the health and wellbeing of employees. Workers require industry specific training about the severity of heat stress and the associated prevention strategies.

Single Session Intermittent Heat Exposure With More Frequent and Shorter Cooling Breaks Facilitates Greater Training Intensity and Elicits Physiological Responses Comparable to Continuous Heat Exposure.

PURPOSE: To investigate the influence of shorter, more frequent rest breaks with per-cooling as an alternative heat-acclimation session on physiological, perceptual, and self-paced maximal cycling performance, compared with continuous heat exposure. METHODS: Thirteen participants completed 1 continuous and 3 intermittent-heat-exposure (IHE) maximal self-paced cycling protocols in a random order in heat (36 °C, 80% relative humidity): 1 × 60-minute exercise (CON), 3 × 20-minute exercise with 7.5-minute rest between sets (IHE-20), 4 × 15-minute exercise with 5-minute rest between sets (IHE-15), and 6 × 10-minute exercise with 3-minute rest between sets (IHE-10). Mixed-method per-cooling (crushed-ice ingestion and cooling vest) was applied during rest periods of all IHE protocols. RESULTS: Total distance completed was greater in IHE-10, IHE-15, and IHE-20 than in CON (+11%, +9%, and +8%, respectively), with no difference observed between IHE protocols. Total time spent above 38.5 °C core temperature was longer in CON compared with IHE-15 and IHE-20 (+62% and +78%, respectively) but similar to IHE-10 (+5%). Furthermore, a longer time above 38.5 °C core temperature occurred in IHE-10 versus IHE-15 and IHE-20 (+54% and +69%, respectively). Sweat loss did not differ between conditions. CONCLUSION: IHE with per-cooling may be a viable alternative heat-acclimation protocol in situations where training quality takes precedence over thermal stimulus or when both factors hold equal priority.