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We live in the information age where a tremendous amount of training information is available. When it comes to that information, much of it is biased, hyped, or stripped of context for each athlete’s individual physiology. New trends come and go, often pushed more by those selling the concepts than by what we know works from decades of experience and historical perspective.
The Foundation of Training
To plan effective training, we need to start with a realistic assessment of the athlete: fitness, strengths, weaknesses, lifestyle, and goals. Endurance sports depend on multiple components:
- Physiological – aerobic pathways, oxygen transport, mitochondrial content and function, fiber recruitment, efficiency, and aerobic capacity.
- Neuromuscular – maximal strength, power, endurance strength, motor unit recruitment, speed, skill, and technique.
- Psychological – lifestyle, goals, focus, commitment, and recovery.
- Nutrition – macronutrient composition, fueling, hydration, training and race nutrition.
A well-rounded program addresses all of these. Narrow approaches that fixate on one method—Zone 2, FTP, Critical Power, double threshold, sweet spot, sprint intervals, lactate threshold—miss the bigger picture. The reality is: all aspects of endurance training belong in the program most of the time, with shifting emphasis depending on the athlete and the goals.
Cutting Through the Noise
The evidence is consistent: endurance performance is built primarily on low-intensity aerobic training, supplemented with higher-intensity work as appropriate for the athlete’s level and objectives.
- Younger athletes often benefit from VO₂max training to build aerobic capacity.
- Mature athletes may balance VO₂max and maximal lactate steady state work.
- Long-distance specialists may rely heavily on steady-state, threshold-oriented intensity.
Strength, endurance strength, speed, power, and technical training must also be programmed in, not just aerobic conditioning.
Trends like Zone 2 or double threshold training have their place, but we can’t let the swinging pendulum blind us to what has consistently worked. Even the definitions themselves are suspect, “Zone 2” means something different to almost everyone, and lactate thresholds are defined in dozens of ways, often with flawed testing protocols. Interpretation errors are rampant, and influencers either downplay the value of hard training or suggest it shouldn’t happen until years of base training are complete. Neither extreme is supported by experience or results.
The Role of Hard Training
Most coaches default to a metabolic lens, but endurance sport also requires speed and force. To improve the aerobic system, you must move faster. That requires:
- Greater fast-force production.
- Increased motor unit recruitment.
- training fast-twitch fibers to behave more oxidatively.
Zone 2 work, alone, produces minimal gains in force or neuromuscular function. The forces are simply too low to stimulate meaningful improvement beyond very long-duration events.
Personal Example
Coming back from long COVID, a year and a half ago, I did 35 endurance sessions in 45 days, with a peak Firstbeat load of ~750 TRIMP. For me, this was a pretty big load of training. The result was clear aerobic improvement: ERG power at low intensity rose from 75–80 watts to 125 watts, and outdoor average speed improved from 13.5 to 15 mph. But neuromuscular capacity lagged, I couldn’t push and sustain higher outputs.
Over several bike erg workouts, I did several three-minute power builds. That exposed the gap: heart rate stayed low, but my legs were fried after three sets. Months of aerobic work hadn’t improved my ability to go harder. Yet, after just a couple of harder workouts, I was able to ride nearly 8 minutes faster over 30 miles, not from metabolic change, but from neuromuscular recruitment. Note the initial gains of this approach a neural, and without continued hard work, that gain would fade back to baseline.
Adaptations from High-Intensity Training
The specific benefits of properly dosed intensity include:
- Central adaptations – increased cardiac output and oxygen delivery.
- Peripheral adaptations – more motor units engaged, increased aerobic enzymes, improved fiber recruitment, better mitochondrial function.
- Strength adaptations – higher force production capacity.
- Buffering adaptations – improved handling of acidosis.
- Efficiency adaptations – higher fractional utilization of aerobic capacity.
My advice: consider current science and trends, but don’t lose focus on what we know is important from your personal experience. And remember that training is multifaceted; there are multiple adaptations to training we need to consider.
Jim Galanes
Coach, competitor, correspondent, commentator—Jim Galanes has spent a lifetime on cross country skis, always serving as a keen observer of our sport. A three-time Olympian in both Cross-Country and Nordic Combined, Jim has tested the theories, initiated the instruction, assessed the results. Now, FasterSkier is thrilled to announce that Jim joins our staff of writers and contributors, adding his unique and time-tested insights to the editorial offerings of this publication.
