What happens mechanically
In a rapid growth phase, long bones lengthen faster than the muscles and tendons around them can adapt. Levers get longer, the centre of mass moves, and the motor programmes that governed running, jumping and cutting last season are now calibrated for a body that no longer exists.
Athletes feel this as clumsiness. Coaches see it as a sudden loss of sharpness in a player who was technically fine three months ago. It has a name in the literature, adolescent awkwardness - and while its size and consistency are debated, the practical experience of it is familiar to anyone working in youth sport.
Step 1
Leg length increases
The fastest lengthening happens in the legs first, then the trunk. Movement patterns are calibrated to old limb lengths.
Step 2
Soft tissue plays catch-up
Muscle-tendon units are stretched over longer bones, reducing available range and increasing traction at attachment sites.
Step 3
Coordination dips
Landing, cutting and sprint mechanics degrade temporarily. Technical performance can look worse despite unchanged effort.
Step 4
Strength arrives
Peak strength and power gains follow peak height by roughly 6-12 months. The athlete typically emerges more powerful than before.
Strength: the lag is the story
Peak height velocity, the fastest point of growth, comes first. Peak weight velocity follows, and peak strength velocity typically arrives six to twelve months after that, particularly in boys where testosterone-driven muscle gain is substantial.
That sequence has a practical consequence: for a period, an athlete is carrying a longer, heavier frame with strength qualities that have not yet caught up. Relative strength, strength per kilogram of body mass - can genuinely fall, and that shows up in anything requiring the athlete to control their own body: jumping, changing direction, decelerating.
Relative timing of the peaks. Bars show sequence and lag, not absolute magnitudes.
Speed: expect a plateau, not a loss
Sprint speed generally continues improving through adolescence, driven by longer levers and greater force production. But it rarely improves smoothly. Many athletes stall for a few months around their spurt as stride mechanics reorganise, then improve sharply once strength arrives.
The mistake is to read a plateau as a decline in talent and respond with more sprint volume at exactly the point where the athlete's tissues are least tolerant of it. Quality over quantity is the right instinct here: short, fully recovered sprint exposures maintain the skill without accumulating the repetition that provokes symptoms.
Endurance and the aerobic side
Absolute aerobic capacity rises with body size through adolescence, but relative capacity, expressed per kilogram, is often flat or slightly reduced during rapid growth in boys as mass increases. A young athlete who feels heavier and slower in the last quarter of matches is usually experiencing this rather than losing fitness.
Aerobic work is well tolerated during a spurt provided it is not delivered entirely through high-impact running. Cycling, rowing and swimming maintain the engine while giving the knees and heels a break.
How to train through the spurt
| Quality | During the spurt | Why |
|---|---|---|
| Strength | Maintain or increase, controlled tempo | Supports the new frame and protects tissue tolerance |
| Plyometrics | Reduce volume and height, keep quality | Landing repetitions are the main irritant at knee and heel |
| Sprinting | Keep short exposures, full recovery | Preserves the skill without accumulating impact |
| Mobility | Targeted, not aggressive stretching | Soft tissue is under tension; forceful stretching often flares symptoms |
| Total volume | Hold steady rather than increase | Growth is itself a load the body is managing |
| Skill work | Increase relative share | Low impact, high value while coordination re-calibrates |
What good handling looks like over a season
- Monthly height measurement, recorded and shared with coaches.
- Two strength sessions a week maintained year-round.
- Jump and landing volume tracked and pulled back during rapid phases.
- One genuine rest day per week and an off-season from the main sport.
- Expectations reset explicitly with the athlete so a plateau is not read as failure.
The message for the athlete
This phase is temporary
Feeling slower, heavier or less coordinated during a growth spurt is a normal stage, not evidence of lost ability. Athletes who keep training with adjusted volume tend to come out of it stronger and faster than they went in.