Spring is the time when fitness is sown – the results are harvested in summer. But many athletes make the same mistake: they think that training more is what it takes to improve. In reality, the key is to train better – and to understand what really happens in the body when you cycle or run.
1. Understand What You’re Really Training
Before talking about methods, it’s useful to understand the two systems that determine speed and endurance:
The aerobic system uses oxygen to produce energy. It’s efficient, sustainable, and trained at low intensity. It is the foundation of endurance.
The anaerobic system produces energy without oxygen, very quickly but only for short periods. It’s what you use during accelerations, explosive climbs, and sprints.
Aerobic and anaerobic training: what are the differences?
Most amateur cyclists and runners spend too much time in an intermediate zone – not low enough to develop the aerobic system, not high enough to stimulate the anaerobic one. The result is training that optimizes neither. This is exactly why the 2PEAK algorithm distributes the workload across zones precisely – to avoid spending weeks in that grey zone that develops neither endurance nor speed.
Z2 or Z3? The choice that shapes your progress
2. The Aerobic Base Is Behind You – Now Intensity Rises
The winter phase had a clear goal: building the aerobic engine. In spring, that “base training” work is done – and the focus changes radically. Volume stabilizes or decreases slightly, but intensity increases in a targeted way. It’s not about doing more, but doing better and more intensely.
Now come the sessions that truly make the difference in racing: hill repeats, threshold sessions, short high-power efforts. Each session has a precise purpose – and starts to look more and more like what awaits you at the start line.
A useful indicator: if in winter you asked “how much”, in spring you should ask “how” and “at what intensity”.
3. Interval Training: Structure Makes the Difference
In spring, interval training becomes the core of training (assuming your first races are in summer). It’s not about pushing harder, but pushing the right way. Poorly structured repeats or those done with tired legs produce fatigue without adaptation.
Three concrete examples of how 2PEAK structures these sessions:
Running – Z5 (6 x 400m): 15 minutes warm-up in Z2, then 6 x 400m repeats in zone 5 with 1:38 recovery in Z2 between each. Long cool-down in Z2. The goal is to stimulate VO2max while maintaining quality on every repeat – not to finish destroyed.
Cycling – Z4 (4 x 6′) + Z4 HIGH (3 x 2′): 15 minutes in Z2, then 4 blocks of 6 minutes in Z4 alternating with Z2 recovery. Followed by 3 shorter but more intense repeats in Z4 HIGH. Long cool-down in Z2. A threshold session that develops sustainable power over long distances.
Swimming – Z3/Z4 with variations: Progressive warm-up, then 5 x 400m in Z3, 9 x 100m in Z4, 6 x 50m in Z3 with progression. Cool-down in Z1. A session that works both endurance and the ability to sustain repeated high-intensity efforts.
The common thread is always the same: targeted intensity, respected recovery, controlled volume.
4. Don’t Neglect Muscular Strength
Performance in endurance sports doesn’t only depend on aerobic capacity – it also depends on the muscular force applied with each pedal stroke or stride. An athlete with a well-developed aerobic engine but weak muscles will struggle to express their full potential.
- Cycling: Strength is trained primarily in the saddle. Low-cadence climbs (50–60 rpm) in a hard gear are the most effective tool: they force the muscles to produce more force with each pedal stroke, developing power without the traumatic impact of maximal repeats.
- Running: Muscular strength is often the neglected factor that separates runners who improve from those who get injured. Hill sprints, reactive strength exercises, and specific glute and core work improve running economy – the ability to go faster while consuming less energy.
Maximize your performance with effective interval training
5. The Lactate Threshold: The Number You Need to Know
If there is one parameter that determines your average speed over long distances, it is the lactate threshold – the maximum intensity at which your body can still clear the lactate produced by the muscles. Training above this threshold for too long leads to lactate accumulation and muscular failure.
Improving the lactate threshold means being able to go faster for longer. It is trained mainly with zone 3–4 work: prolonged efforts just below or at the threshold, repeated over time.
PEAK provides specific performance tests directly within the platform to measure your lactate threshold and calibrate your training zones.
6. Recover as if It Were Part of Training
Speed and endurance don’t improve during training – they improve during recovery. During effort, the body undergoes controlled stress; during rest, it adapts, strengthens, improves (supercompensation). Without adequate recovery, stimuli accumulate without producing adaptation – and the result is chronic fatigue.
The recovery pillars athletes tend to undervalue:
- Sleep: Fewer than 7 hours seriously compromises progress.
- Post-workout nutrition: The 30–60-minute window after training is crucial for glycogen resynthesis and muscle repair. Carbohydrates and proteins together – not just one of the two.
- Deload weeks: Every 3 weeks or so, reducing volume is essential. No athlete training 8 hours a week with optimal recovery will progress more slowly than one training 12 hours with insufficient recovery.
7. Let Data Guide Your Decisions
Training by feel in spring is risky. Beautiful days tempt you to push even when the body isn’t ready, and the feeling of fitness doesn’t always match actual fitness. Data eliminates this ambiguity.
Some of the most useful parameters to monitor:
- Resting heart rate: An increase of 5–7 bpm from the norm is often the first signal of overload.
- HRV (Heart Rate Variability): Low values indicate that the autonomic nervous system is under stress – a signal to reduce the load.
- Critical power: Indicates the maximum intensity you can sustain for a long time without exhausting yourself. Monitoring it over time reveals whether your aerobic system is growing – one of the most reliable indicators of real improvement.