By: Andrew Cantor
Chaski Coach Resident Andrew is a former collegiate runner for Salisbury University who competed in cross country and track and field events. He discusses training plans and running philosophies. Aside from running, Andrew is also full-time commercial banker and a biker too!
Critical Velocity or CV training was initially noted in 1960s research as being the highest intensity of exercise one could exert indefinitely without fatigue. This definition has changed several times over the last sixty years as further research has been conducted.
The general and broad conclusion is that critical velocity is highly correlated with 10K race effort and that this velocity is significantly correlated with running performances ranging from the 800 meters on up to the marathon.
Research supports the idea that once you begin running at a pace faster than your critical velocity, you will reach VO2 MAX over time.
By training at the critical velocity, one can reach and most importantly, maintain, a high percentage of their VO2 MAX (as well as lactate steady state) for the duration of the individual repetitions of the workout, leading to both VO2 MAX and lactate threshold improvements. Thus, one can view critical velocity as a barometer of aerobic endurance.
Running Coach Tom “Tinman” Schwartz is known for the recent popularization of CV training. He believes that that CV is a pace that can be sustained for up to 45 minutes (depending on the athlete’s ability and current fitness).
His research shows that by training an athlete at their critical velocity, they improve their lactate threshold while simultaneously improving their VO2 Max.
The USATF Coaches Education Program’s % of VO2 MAX method of determining training paces is broken down as follows:
● 800 meters 120-136% of VO2 MAX
● 1500 meters 110-112% of VO2 MAX
● 3000 meter 100-102% of VO2 MAX
● 5000 meters 97-100% of VO2 MAX
● 10000 meters 88- 92% of VO2 MAX
● Half-Marathon 85-88%% of VO2 MAX
● Marathon 82%-85% of VO2 MAX
Coach Schwartz believes CV training is about extendibility. His philosophy and goals for his distance runners boil down to extending speed over a greater distance at the same effort as previous workouts. When adding these sessions to a training program, one will be able to improve their fractional utilization of VO2 MAX (the aforementioned 88-92%).
By improving your fractional utilization, you can perform at a faster pace for a longer distance at a lower percentage of VO2 MAX velocity, thereby bringing about improvement across all distances relating to submaximal velocities. Using critical velocity sessions will also allow the runner to go longer and faster at a higher blood lactate concentration level.
In essence, CV training is designed to be a hard, but not-too-hard running pace that improves the aerobic capacity and recruitment of the fast-twitch muscle fibers responsible for endurance and sustainable intermediate speed. These sessions provide high quality work without over-taxing the athlete physically or mentally.
Long-distance runners use primarily slow-twitch muscle fibers (type I). Slow-twitch fibers use oxygen and are more fatigue resistant whereas fast-twitch fibers (IIa and IIx) generate speed but fatigue quickly. Type IIx uses strictly anaerobic energy pathways and lasts only a very short amount of time before fatiguing.
Contrary to conventional thinking, one does not run races even at long distances such as marathons or ultras on slow-twitch fibers alone. Type IIa fast-twitch fibers have properties of both slow-twitch and fast-twitch fibers.
Comparatively, Type IIA muscle fibers can produce higher output than ST fibers, while still using oxygen as their primary energy pathway. CV intervals recruit type IIa muscle fibers which benefit an athlete’s performance in every distance from the 800 to the ultramarathon.