Does Fatigue Impact Static and Dynamic Balance Variables in Athletes with Previously Ankle Injury?

International Journal of Exercise Science 12(3): 1121-1137, 2019. Ankle injury, resulting in deficits in static and dynamic balance, can result in significant time loss to sport, affect daily activities and potentially place athletes at greater risk of re-injury. In order to identify athletes at risk of ankle injury accurate and reliable balance assessment tools are required. The purpose of the current study was to quantify reliability of static and dynamic balance variables in currently healthy, previously injured, athletes (n = 19) and assess the impact of an intense intermittent zig-zag running protocol to volitional exhaustion, rated by RPE, on balance variables. A test re-test design assessed short-term reliability and measurement error by computing ICC and 95% limits of agreement (LoA). The Y balance test was deemed a reliable measuring tool for assessing dynamic balance, recording strong reliability (ICC = 0.96, 95% LoA from -95.7 to 105.8%). A HURlabs iBalance force platform assessed the static balance variables sway velocity and C90area; sway velocity (mmˑs-1) recorded strong reliability (ICC = 0.79). Significant post-fatiguing protocol increases (p \u3c 0.001) were detected in single-leg static balance for both C90area (mm2) and sway velocity (mmˑs-1) assessed on stable and unstable surfaces (stable: 227 ± 84 vs. 366 ± 146 mm2and 18.6 ± 4.2 vs. 22.9 ± 5.3 mmˑs-1: unstable; 275 ± 128 vs. 370 ± 140 mm2and 19.3 ± 4.3 vs. 21.5 ± 4.0 mmˑs-1). Non-significant post-fatiguing protocol differences (p \u3e 0.05) were detected in dynamic balance variables (anterior, posteromedial, posterolateral and composite reach scores) measured at 4-min after completing the protocol. Further research should investigate the effects of fatigue on dynamic YBT variables immediately post-exercise and determine if differences exist when comparing previously injured and un-injured limbs

Comparison of Balance Variables Across Active and Retired Athletes and Age Matched Controls

International Journal of Exercise Science 14(3): 76-92, 2021. Postural control is a major falls risk factor, therefore identifying protective mechanisms is essential. Physical activity enhances postural stability but effect duration has been minimally researched. The current study investigated if prolonged early life training exposure protected neuromuscular balance processes later in life. Static and dynamic balance variables were assessed in 77 healthy adults. Two age ranges (18 - 35yr, young; \u3e 50yr, retired) were divided into weight bearing athlete and control groups; young athlete (YA), young control (YC), retired athlete (RA) and retired control (RC). Static balance was quantified using force platform derived sway velocity (mm.s-1) and C90area (mm2) data (stable and unstable surfaces, eyes open and closed) Dynamic balance was assessed using the Y balance test (YBT). Results demonstrated significant age effect across groups. However, an athletic effect was evident only assessing dynamic balance and static time to error variables. Mean time to error data (YA, 27.8 ± 5.8; YC, 20.5 ± 11.1; RA, 9.4 ± 8.5; RC, 8.6 ± 9.1 s) recorded significant age and athletic effects for the most challenging condition completed (single leg stance, eyes closed, stable surface). Mean maximum YBT composite score (YA, 90.0 ± 5.4%; YC, 83.6 ± 6.5%; RA, 80.8 ± 10.7%; RC, 72.4 ± 15.5%) demonstrated an age effect, and also identified a group effect in the retired cohorts. The current study supports research highlighting declined balance with ageing. Overall, former athleticism did not significantly enhance static balance in later life. Dynamic balance incorporates muscle strength possibly inferring a protective role in former athletes

Prediction of Rowing Functional Threshold Power using Body Mass, Blood Lactate and GxT Peak Power Data.

International Journal of Exercise Science 16(4): 31-41, 2023. Functional Threshold Power (FTP) is a validated index of a maximal quasi steady-state cycling intensity. The central component of the FTP test is a maximal 20-min time-trial effort. A model to predict FTP from a cycling graded exercise test (m-FTP) was published that estimated FTP without the requirement of the exhaustive 20-min time-trial. The predictive model (m-FTP) was trained (developed to find the best combination of weights and bias) on a homogenous group of highly-trained cyclists and triathletes. This investigation appraised the external validity of the m-FTP model vis-à-vis the alternate modality of rowing. The reported m-FTP equation purports to be sensitive to both changing levels of fitness, and exercise capacity. To assess this claim, eighteen (7 female, 11 male) heterogeneously-conditioned rowers were recruited from regional rowing clubs. The first rowing test was a 3-min graded incremental test with a 1-min break between increments. The second test was a rowing adapted FTP test. There were no significant differences between rowing FTP (r-FTP) and m-FTP (230 ± 64 versus 233 ± 60 W, respectively, F = 1.13, P = 0.80). Computed Bland-Altman 95% LoA between r-FTP and m-FTP were (-18 W to + 15 W), sy.x was 7 W, and 95 %CI of regression were 0.97 to 0.99. The r-FTP equation was demonstrated to be effective in predicting a rowers 20-min maximum power; further appraisal of the physiological response to rowing for 60-min at the corresponding calculated FTP requires investigation

Is the FTP Test a Reliable, Reproducible and Functional Assessment Tool in Highly-Trained Athletes?

International Journal of Exercise Science 12(4): 1334-1345, 2019. The aim of the current study was to assess reliability of the Functional Threshold Power test (FTP) and the corresponding intensity sustainable for 1-hour in a “quasi-steady state”. Highly-trained athletes (n = 19) completed four non-randomized tests over successive weeks on a Wattbike; a 3-min incremental test (GxT) to exhaustion, two 20-min FTP tests and a 60-min test at computed FTP (cFTP). Power at cFTP was calculated by reducing 20-min FTP data by 5% and was compared with power at Dmax and lactate threshold (TLac). Ventilatory and blood lactate (BLa) responses to cFTP were measured to determine whether cFTP was quasi-steady state. Agreement between consecutive FTP tests was quantified using a Bland-Altman plot with 95% limits of agreement (95% LoA) set at ± 20 W. Satisfactory agreement between FTP tests was detected (95% LoA = +13 and -17 W, bias +2 W). The 60-min effort at cFTP was successfully completed by 17 participants, and BLa and ventilatory data at cFTP were classified as quasi-steady state. A 5% increase in power above cFTP destabilized BLa data (p \u3c 0.05) and prompted VO2 to increase to peak GxT rates. The FTP test is therefore deemed representative of the uppermost power a highly-trained athlete can maintain in a quasi-steady state for 60-min. Agreement between repeated 20-min FTP tests was judged acceptable

Do Critical and Functional Threshold Powers Equate in Highly- Trained Athletes?

International Journal of Exercise Science 14(4): 45-59, 2021. The purpose of this investigation was to determine whether Critical Power (CP) and Functional Threshold Power (FTP) can be used interchangeably for a highly-trained group of cyclists and triathletes. CP was ascertained using multiple fixed load trials and FTP determined from a single cycling trial. Three different models for the determination of CP were initially addressed, one hyperbolic (Hmodel) and two linear (Jmodel and Imodel). The Jmodel was identified as most appropriate for a comparison with FTP. The Jmodel and FTP were not found to be interchangeable as ANOVA detected significant differences (282 ± 53 vs. 266 ± 55 W, p \u3c 0.001) between these indices and the associated Bland-Altman 95% limits of agreement exceeded those set a priori. As the Jmodel was found to be consistently higher than FTP, a correction factor was posited to anticipate CP from FTP in this homogenous group of athletes using the mean bias (16 W). An alternate method for assessing CP trial intensities using Dmax as a proxy for ventilatory threshold is also proposed. The concept of both CP and FTP representing a maximal metabolic steady-state requires further investigation as the mechanical power at CP was significantly greater than at FTP

Acute Effects Of 24-h Sleep Deprivation On Salivary Cortisol And Testosterone Concentrations And Testosterone To Cortisol Ratio Following Supplementation With Caffeine Or Placebo

International Journal of Exercise Science 10(1): 108-120, 2017. Caffeine has become a popular ergogenic aid amongst athletes and usage to improve athletic performance has been well documented. The effect of caffeine on anabolic and catabolic hormones in a sleep-deprived state has had little investigation to date. The purpose of the current study was to investigate the potential of caffeine to offset the effects, if any, of short-term sleep deprivation and exercise on an athlete’s testosterone and cortisol concentrations via salivary technique. Eleven competitive male athletes volunteered to be part of this prospective double-blinded study. Three test days were scheduled for each athlete; one non-sleep deprived, one sleep-deprived with caffeine supplementation (6 mg.kg-1) and one sleep-deprived with placebo ingestion. Sleep deprivation was defined as 24-h without sleep. Each test day was composed of 2 aerobic components: a modified Hoff test and a Yo-Yo test. Testosterone and cortisol concentrations were measured via salivary analysis at 4 different time-points; T1 to T4, representing baseline, and pre- and post-aerobic components, respectively. Overall no significant differences were detected comparing the different sleep states for testosterone or cortisol concentrations. A trend existed whereby the sleep-deprived with caffeine ingestion state mirrored the non-sleep deprived state for cortisol concentration. Therefore, caffeine supplementation may have potential benefits for athletes during short-term aerobic exercise when sleep-deprived. An increase in mean testosterone concentration post-aerobic exercise was only observed in the sleep-deprived with caffeine ingestion state

Effects of Carbohydrate-Protein Ingestion Post-Resistance Training in Male Rugby Players

Evidence suggests that carbohydrate-protein (CHO-PRO) drinks post-exercise are an advantageous nutritional recovery intervention. Resistance trained (n = 14, mean ± SD; age 19 ± 1 yr, mass 95 ± 9 kg, % fat 17 ± 4 % and BMI 28.5 ± 1.8 kg.m-2) male rugby players participated in a study investigating effects of carbohydrate (CHO) and CHO-PRO drinks on subsequent resistance exercise performance. Following an initial resistance training (RT) protocol consisting of 8 circuits of 5 discrete exercises at 10 repetition maximum (RM), participants received 10 mL.kg-1 BM of randomised sports drink (LCHO, HCHO and CHO-PRO) on completion of the RT protocol and at 120 min into a 240 min recovery period. Post-recovery, participants completed a test to failure (TTF) protocol performing as many circuits of the same exercises at 10-RM to failure. Individual exercise cumulative load (ƩW) lifted and total work capacity (TWC) for each trial was recorded. Both ƩW and TWC were normalised for body mass (kg.kg-1 BM). Data were analysed using repeated measures ANOVA with post-hoc Student-Neuman-Keuls pair-wise comparisons (P\u3c0.05). Despite large intra-subject variability between trials, TWC normalised for body mass was significantly greater following CHO-PRO compared with HCHO and LCHO (188 ± 26 vs. 157 ± 21 and 150 ± 16 kg.kg-1 BM, respectively; P\u3c0.05). The ƩW lifted after ingestion of HCHO and LCHO were not significantly different despite differing CHO and caloric content. The CHO-PRO induced enhancement of recovery was possibly due to higher rates of glycogen restoration after the initial glycogen depleting RT protocol

Effect of Seat Tube Angle and Exercise Intensity on Muscle Activity Patterns in Cyclists

International Journal of Exercise Science 10(8): 1145-1156, 2017. Previous studies have reported improved efficiency at steeper seat tube angle (STA) during ergometer cycling; however, neuromuscular mechanisms have yet to be fully determined. The current study investigated effects of STA on lower limb EMG activity at varying exercise intensities. Cyclists (n=11) were tested at 2 workloads; 160W and an individualised workload (IWL) equivalent to lactate threshold (TLac) minus 10%δ (derived from maximal incremental data), using 3 STA (70, 75 and 80°). Electromyographic data from Vastus Medialis (VM), Rectus Femoris (RF), Vastus Lateralis (VL) and Biceps Femoris (BF) were assessed. The timing and magnitude of activation were quantified and analysed using a two-way ANOVA. STA had significant (P \u3c 0.05) effects on timing of onset and offset of VM, timing of offset of VL, and angle at peak for RF, all occurring later at 80 vs. 70° STA at IWL. In RF, increased activity occurred during the first 108° of the crank cycle at 80 vs. 70° at IWL (P \u3c 0.01). As most of the power in the pedal stroke is generated during the mid-section of the down-stroke, movement of the activation range of knee extensors into the predominantly power phase of the pedal stroke would potentially account for increased efficiency and decreased cardio-respiratory costs. Greater activity of bi-articular RF, in the first 108º of the crank cycle at IWL (80 vs. 70º) may more closely resemble the pelvic stabilising activity of RF in running biomechanics; and potentially explain the more effective transition from cycling to running reported in triathletes using steeper STA

EFFECT OF KAYAK ERGOMETER ELASTIC TENSION ON UPPER LIMB EMG ACTIVITY AND 3D KINEMATICS

Despite the prevalence of shoulder injury in kayakers, limited published research examining associated upper limb kinematics and recruitment patterns exists. Altered muscle recruitment patterns on-ergometer vs. on-water kayaking were recently reported, however, mechanisms underlying changes remain to be elucidated. The current study assessed the effect of ergometer recoil tension on upper limb recruitment and kinematics during the kayak stroke. Male kayakers (n = 10) performed 4 by 1 min on-ergometer exercise bouts at 85%VO2max at varying elastic recoil tension; EMG, stroke force and three-dimensional 3D kinematic data were recorded. While stationary recoil forces significantly increased across investigated tensions (125% increase, p < 0.001), no significant differences were detected in assessed force variables during the stroke cycle. In contrast, increasing tension induced significantly higher Anterior Deltoid (AD) activity in the latter stages (70 to 90%) of the cycle (p < 0.05). No significant differences were observed across tension levels for Triceps Brachii or Latissimus Dorsi. Kinematic analysis revealed that overhead arm movements accounted for 39 ± 16% of the cycle. Elbow angle at stroke cycle onset was 144 ± 10°; maximal elbow angle (151 ± 7°) occurred at 78 ± 10% into the cycle. All kinematic markers moved to a more anterior position as tension increased. No significant change in wrist marker elevation was observed, while elbow and shoulder marker elevations significantly increased across tension levels (p < 0.05). In conclusion, data suggested that kayakers maintained normal upper limb kinematics via additional AD recruitment despite ergometer induced recoil force