Training notes
The 12-week cutoff
Most plans walk you through one energy system at a time.
Big base of Zone 2. Then tempo. Then threshold. Then VO2. Or hills and low-RPM strength, then speed.
That works when you are still building the engine. It fails when you are trying to race.
Who this is for
This switch is intermediate and advanced only.
Beginners stay in traditional periodization all year. They are still building overall aerobic fitness. Concurrent is the wrong tool. You do not sharpen five systems when the base is not there yet.
Traditional periodization
One block. One focus.
You spend weeks loading one zone or one quality. Endurance gets very good. Then you shift to strength, power, or speed. That one comes up. The one you just left starts to fade.
Same pattern if you think in “types of fitness” instead of zones: endurance block, then a strength/power block, then a speed block. You finish each block fit in that system. The others are not.
That is not a theory problem. Unused qualities decay on a clock.
- Aerobic endurance holds ~25–35 days after you stop training it
- Threshold / glycolytic work holds ~14–22 days
- Top-end speed holds ~2–8 days
So a long endurance block leaves you strong in Zone 2 and quiet on the top end. A long VO2 block does the reverse. Fine in the off-season. A problem when the A-race is close.
Why concurrent exists
A race does not ask for one zone.
You need endurance to stay in it. Threshold / time-trial speed to go when it matters. Top-end to finish or cover. If any of those is missing, you are not race-fit. You are block-fit.
Concurrent means those systems stay in the same week. Not equal volume. Not smash everything. Keep each quality alive so nothing goes quiet.
This is not new, and it is not gym-bro.
Westside Barbell’s conjugate method is concurrent by design: max strength, speed-strength, and work capacity in the same week, not in separate seasons. The Soviet and Bulgarian strength systems that fed it were built the same way. Elite performance needed several qualities live at once. Train one, park the others, and the parked ones become the limiter.
Same logic on the bike. Inside 12 weeks of an A-race or race-season start, you cannot afford a block that makes one system huge and lets the others sleep.
The rule
Beginner: traditional periodization all year. No concurrent phase.
Intermediate / advanced:
- ≥12 weeks from the A-race or race-season start → traditional (build the quality)
- ≤12 weeks out → concurrent (mandatory)
The 12-week line is the VeloForge cutoff. The science underneath it is the residual clock plus what a race actually demands. We do not pretend a paper published “switch on week 12.” We use 12 weeks because that is enough time for unused top-end to fade, and not enough time to rebuild it if you stay in one-zone blocks.
Citations
- Issurin VB. New horizons for the methodology and physiology of training periodization. Sports Med. 2010;40(3):189–206. Residual durations: aerobic ~30±5 days, anaerobic glycolytic ~18±4, max speed ~5±3.
- Issurin VB. Benefits and limitations of block periodized training approaches. Sports Med. 2016;46(3):329–338.
- Mujika I, Padilla S. Detraining: loss of training-induced physiological and performance adaptations. Part I. Sports Med. 2000;30(2):79–87.
- Bompa TO, Haff GG. Periodization: Theory and Methodology of Training. 5th ed. Human Kinetics; 2009. Long preparatory / foundation work for less-trained athletes.
- van Erp T, Sanders D. Demands of professional cycling races: influence of race category and result. Eur J Sport Sci. 2021. Higher short-duration power tracks with better results — races ask for more than one system.
- Padilla S, Mujika I, et al. Exercise intensity and load during mass-start stage races in professional road cycling. Med Sci Sports Exerc. 2001;33(5):796–802.
- Rønnestad BR, Hansen EA, Raastad T. In-season strength maintenance training increases well-trained cyclists’ performance. Scand J Med Sci Sports. 2010;20(6):e170–e177. Drop a quality in-season and you lose the transfer.
- Verkhoshansky YV. Fundamentals of Special Strength-Training in Sport. 1977. Concurrent development of special strengths for high-level athletes.
- Simmons L. Westside Barbell conjugate / concurrent method. Multiple qualities in the same week, not sequential seasons.
Notes from training and coaching. Building VeloForge for serious riders making these calls with their own data. Product waitlist: join.veloforge.app.