Begin by clearly situating your research question: “How does a single high-intensity interval training (HIIT) session compared with an equal-duration steady-state run influence countermovement jump height and neuromuscular fatigue (measured by peak torque) in competitive cross-country runners?” Define your key terms (HIIT, steady-state run, countermovement jump height, peak torque, competitive cross-country runners) and justify the choices of participants, controls and measurement times. Design a repeated-measures experiment where each runner completes both conditions separated by adequate recovery; control for warm-up, time of day, nutrition, and prior training to minimise confounding variables. Select valid, reliable tools: a force platform or jump mat for countermovement jump, an isokinetic dynamometer for peak torque or a well-validated hand-held dynamometer if a lab dynamometer is unavailable, and a heart rate monitor or RPE scale to standardise intensity. Plan sample size with a basic power consideration (acknowledge IB constraints) and include ethical steps: consent, participant safety, and how you will handle unexpected injuries or dropouts. State your independent variable (session type), dependent variables (jump height and peak torque), and any covariates (fatigue, sleep, menstrual cycle where relevant). Keep the research question exactly as provided and do not alter it in your write-up.
Collect data systematically and document every procedural detail so your methods are reproducible and defensible in the Internal Assessment rubric. Before and immediately after each session, measure countermovement jump height and peak torque at standardised joint angles; consider also measuring after short recovery intervals (e.g., 15 and 30 minutes) if time allows and if it fits your approved protocol. Use clear data sheets, label conditions, and randomise the order of sessions to reduce order effects. In your analysis, calculate descriptive statistics (means, SDs) and use appropriate inferential tests for within-subject comparisons — typically paired t-tests or Wilcoxon signed-rank tests if data are non-normal. Report effect sizes and confidence intervals, and check assumptions (normality, sphericity if repeated measures ANOVA). Include simple graphs (boxplots or bar charts with error bars) to illustrate changes.
When writing, structure the essay to match IB criteria: concise introduction linking background literature to your research question, detailed methods, clear results, and a focused discussion. Interpret findings in light of physiological mechanisms (e.g., metabolic demand, muscle recruitment, neuromuscular transmission, and fatigue pathways) and compare with at least a few peer-reviewed studies. Acknowledge limitations (sample size, measurement constraints, ecological validity) and suggest realistic improvements and practical applications for cross-country runners. Conclude by directly answering the research question using your data, and ensure your references follow a consistent academic format.