Every run costs head and neck loading, training included. How to dose runs across a season, what to log, and when to strike a run from the plan.
The counting unit of your season is not the number of competitions but the number of runs. In a group of 12 elite athletes measured across a complete World Cup tour, the frequency and magnitude of head acceleration events were similar between training and competition [1]. Translated: a training run is not a soft run. Anyone planning their load from start lists is planning past reality.
The order of magnitude: head acceleration events above 8 g were frequent, with peaks around 12.4 ± 3.9 g in men and 11.9 ± 3.5 g in women — yet across the entire tour only a single concussion occurred, at a time-loss injury incidence of 24.55 per 1,000 athlete exposures [1]. Many small impacts, rarely a big one. That combination is exactly what makes management so hard — there is no event forcing you to look.
Because the actual problem does not announce itself. A systematic review of sliding sports describes "sled head" as headache persisting minutes to days after the runs, running subclinically and frequently going unreported; 13 to 18 per cent of all elite sliding athletes are affected by concussions, and whether the cause is concussion, subconcussion or neck overload is unresolved [2]. Those figures apply to sliding sports collectively, not to bobsleigh in isolation.
Count runs, not days. Since frequency and magnitude of head events barely differed between training and competition [1], every trip is a full loading unit. A training block of eight runs costs you more than a race weekend of four. Plan the season from that number, not from result pressure.
Sled head is defined by headache persisting minutes to days after the runs and is frequently unreported [2]. A symptom that is systematically underreported has to be systematically asked for: every evening, the same four questions, on a scale from 0 to 10. What you note only when needed, you never note.
The repeated impact and G loads are transmitted through the spine and pelvis and predispose to cervical and lumbar pain, disc pathology and stress injuries to ribs and vertebrae; forces above 4 to 5 G in high-speed curves are cited [3]. That is a clinical assessment of the loading pattern, not an incidence figure. For load management it means: back and rib pain are loading signals, not background noise.
Three that have proven themselves: headache still present the following day. The same symptom twice in one week. Visual disturbance or nausea after a run — immediately, without a second opinion at the side of the track. Write your criteria down before a season starts, because in January you will otherwise negotiate them against a start position.
In winter sport, energy expenditure, glycogen and fluid turnover and iron turnover all rise while cold simultaneously suppresses appetite — a structural risk of an energy deficit across the season [5]. An under-fuelled athlete recovers worse between runs. Plan meals by the clock, not by hunger.
Strengthening the cervical musculature reduced concussion incidence in men's rugby by around 45 per cent, and the predictor is isometric neck strength rather than neck circumference — but the overall evidence is inconclusive, the optimal dose unknown, and for women's rugby the evidence is missing [6]. This is transfer evidence from other sports: solid enough to train, too thin to promise protection.
This guide provides dosing and monitoring — no diagnosis and no return-to-play protocol. Whether you may slide again after symptoms is decided exclusively by sports medicine, not by a coaching team and certainly not by the affected person. The interdisciplinary framework for prevention and return to sport in the sliding athlete is described precisely for that purpose [3].
Seek medical assessment for: headache persisting overnight; any visual disturbance; nausea or dizziness after a run; numbness or loss of strength in arm or hand; persistent rib or spinal pain. None of that belongs in a self-assessment — the loading zones are known [3], and the symptoms are systematically underreported anyway according to the review [2].
For perspective without alarmism: at one large track, across 43,200 runs in four years, injuries occurred on roughly 0.5 per cent of all runs and serious injuries on under 0.1 per cent [4]. The individual risk is small — which is exactly why volume is the lever.
Track your cumulative run count across the season as a line, not a table — and overlay the symptom scale. What you then see, nobody else does: whether your headache days are randomly distributed or cluster after blocks of high run density. Because training and competition runs load you similarly [1] and sled head lingers minutes to days [2], the relationship never sits in the individual day but in the weekly average. After one season you know your personal run density at which things tip — and that is the only number that genuinely helps you in season two.
There is no universal number — the available evidence offers no validated ceiling. What it does offer is the management variable: runs, not competitions. Frequency and magnitude of head events barely differed between training and competition [1], so every trip counts equally. You find your personal limit only through a log.
Headache persisting minutes to days after the runs, running subclinically and frequently going unreported [2]. Whether concussion, subconcussion or neck overload lies behind it is unresolved [2]. It can only be recognised through daily, structured logging — not through memory.
According to the World Cup measurement, yes: frequency and magnitude of head acceleration events were similar between training and competition [1]. Events above 8 g were frequent, with peaks around 12.4 g in men and 11.9 g in women [1]. A training run is therefore not a reduced load.
Because the repeated impact and G loads are transmitted through spine and pelvis. Described consequences are cervical and lumbar pain, disc pathology and stress injuries to ribs and vertebrae, at forces above 4 to 5 G in high-speed curves [3]. That is an assessment of the loading pattern, not an incidence figure.
It is plausible but not proven. In men's rugby, strengthening the cervical musculature reduced incidence by around 45 per cent, and the predictor is isometric neck strength rather than neck circumference [6]. The overall evidence, however, is inconclusive, the optimal dose unknown, and no dedicated evidence exists for bobsleigh [6]. Train it: yes. Rely on it: no.