ECSS Paris 2023: CP-AP19
INTRODUCTION: Many sports - including Australian Football (AF) - conduct training sessions in varying environmental conditions, which due to a range of acute physiological effects may alter the resultant internal training load for an athlete independent of the external load completed. Being able to predict changes in internal load based on the combination of environmental conditions and expected external training loads would allow for practitioners to plan and potentially alter training sessions to ensure the optimal exposure to training stimulus. This study aimed to determine the effect of differing environmental conditions on internal training load at a given external load in elite AF athletes to create a model to predict internal training load based. METHODS: Professional AF athletes (n=52) undertook 18 weeks of training across two pre-seasons. Environmental conditions, internal training load (training impulse (TRIMP) and TRIMP per minute) and external load from Global Positioning System (GPS) data (total distance, very high-intensity running (VHIR) distance and duration) were recorded at every training session. Multilevel mixed-effects linear models were used to produce a predictive model for internal training load which was tested for validity using a holdback sample RESULTS: Prediction models were created which resulted in no differences between measured and predicted TRIMP and TRIMP per minute values (p > 0.05). For TRIMP and TRIMP per minute there was good absolute agreement (bias of -9.7 arbitrary units [AU] and -0.08 AU/min, no significant difference between measured and predicted p = 0.59 and p = 0.38 respectively). There was also good relative agreement between measured and predicted values (r = 0.66 and 0.46, p = < 0.001 and p = < 0.001). CONCLUSION: Internal training load can be predicted from external load and environmental conditions during team sport training sessions. These predictions could be used to inform adjustments to training load prescription under differing environmental conditions.
Read CV Max NelsonECSS Paris 2023: CP-AP19
INTRODUCTION: Concussions are a significant health risk in high school American football, given their potential to cause both immediate and long-term neurological impairments. As awareness of concussion risks increases, there is a pressing need to develop and implement effective prevention strategies to safeguard young athletes. The neck plays a crucial role in stabilizing the head during impacts, and emerging research suggests that strengthening neck muscles may reduce the risk of concussion by limiting excessive head movement during collisions [1,2,3]. This study investigates the effect of neck strengthening exercises on concussion incidence among high school American football athletes over the 2022-2024 seasons. The primary objective is to determine whether incorporating neck exercises can reduce concussion rates, thereby supporting their integration into high school football training programs. METHODS: Certified Athletic Trainers (ATCs) affiliated with a California State University campus were recruited. Inclusion criteria required ATCs to be 25-65 years old, have 3 years of concussion data (covering the 2022-2024 seasons), and work with a high school American football team. Data were collected via a Qualtrics XM survey reporting physician-confirmed concussions, athlete numbers, athletic exposures (scrimmages, practices, games), and use of neck strengthening exercises during the 2022-2024 seasons; athletes with recent or ongoing concussion symptoms were excluded. One school served as a control without neck exercises, while 3 schools implemented neck training using weighted cervical movements, resistance-based exercises, or Iron Neck equipment with school-specific protocols. RESULTS: Schools implementing neck strengthening programs reported consistently lower concussion rates compared with the school without neck exercises across the 2022-2024 seasons. In 2022, concussion rates ranged from 2.9-4.0% at schools with neck exercises versus 14.2% at the control school. Similar trends were observed in 2023 (1.9-5.8% vs. 15.0%) and 2024 (2.6-8.3% vs. 14.2%). Concussion incidences included scrimmages, games, and practices, consistently lower at schools with neck exercise programs. CONCLUSION: Preliminary findings suggest that neck strengthening exercises may contribute to reduced concussion rates in high school American football athletes. However, variability across schools and potential confounding factors such as protective gear, exercise type, athlete conditioning, and coaching style, warrant cautions interpretation. Larger, controlled studies incorporating standardized neck interventions and objective neck strength assessments are needed to clarify the role of neck strengthening in concussion prevention. References 1) Eckner et al, AM J Phys Med Rehabil, 2018. 2) Felix et al, J Sci Med Sport, 2024. 3) Whittaker et al, J Orthop Sports Phys Ther, 2023.
Read CV KyungMo HanECSS Paris 2023: CP-AP19
INTRODUCTION: Classical threshold concepts (VT1/VT2; lactate thresholds) are typically derived from incremental laboratory protocols, yet team-sport reality includes disruptor bouts and a reversed (decreasing-intensity) workload structure. We hypothesized that lactate alone becomes non-informative during field recovery kinetics, whereas acid–base and blood-gas logistics better and faster track substrate switching and recovery biology. METHODS: Thirty-eight elite American football players (EFL) completed a standardized postprandial, field-ready performance test: mixed meal + digestion, then an in-lab stepwise warm-up and incremental YMCA protocol, immediately followed by a 1-min “disruptor” all-out bout. The subsequent field phase was intentionally reversed (decremental): high-demand mixed drills/CrossFit-type work transitioned to lower-intensity aerobic running, then stretching and passive recovery, reflecting match-like load followed by progressive unloading. Venous samples were repeatedly obtained via cannula and analyzed point-of-care for pH (H⁺ load), pO₂, pCO₂ and lactate. Indirect calorimetry quantified substrate kinetics (FFA contribution). RESULTS: A key marker finding was threshold-equivalent lactate under two physiologically different conditions: YMCA vs the field aerobic-run phase (YMCA: 5.95 ± 1.78 vs aerobic run: 6.24 ± 1.98 mmol·L⁻¹, NS). Despite similar lactate, the accompanying regulatory milieu diverged: Acid–base/H⁺: YMCA H⁺ 5.33 ± 0.82 nmol·dL⁻¹ (≈pH 7.27) vs aerobic run H⁺ 4.59 ± 0.53 (≈pH 7.34), p<0.001. O₂–CO₂ clearance: pO₂/pCO₂ YMCA 0.79 ± 0.37 vs aerobic run 0.97 ± 0.41, p<0.001. Substrate kinetics: FFA utilization YMCA 12.66 ± 11.14% vs aerobic run 31.10 ± 13.66%, p<0.001. CO₂ elimination showed a FEtCO₂ plateau, whereas O₂ availability remained intensity-dependent (as indicated by SmO₂), shaping the pO₂/pCO₂ response and aligning with higher field CHO reliance (HIF-1α–linked) despite unchanged lactate. Insulin increased during passive recovery vs aerobic run (p<0.01) despite a parallel elevation in whole-body FFA utilization, supporting dissociation of hormonal control from substrate oxidation. CONCLUSION: In a field-realistic, reversed workload sequence, lactate can remain “high/threshold-like” while pH/H⁺, pO₂/pCO₂, and fat utilization normalize; thus, lactate becomes a false state marker of metabolic readiness after disruptor bouts. Recovery should be interpreted through integrated O₂/CO₂ logistics and acid–base control: intensity-dependent reductions in O₂ availability likely destabilize HIF-1α–linked regulation and promote higher CHO reliance even at similar lactate. Active (low-intensity) vs passive recovery represents a metabolic divergence: active recovery sustains oxidative flux and lactate reutilization in local muscles (via monocarboxylate transporter 1, MCT1) and supports by-product handling, whereas passive recovery favors persistence of uncoupling. This marks the distinction between fatigue accumulation and adaptation.
Read CV Gabor KurucsaiECSS Paris 2023: CP-AP19