Sean Brosnan’s Training System: How Newbury Park Built the Greatest High School XC Dynasty in History
In 2016, Sean Brosnan walked into Newbury Park High School cross country and told his athletes and their parents something no coach in that program’s history had ever said with credibility: we are going to win a state championship within four years.
The program had not qualified for the California State Championships in 25 years. There was no reasonable basis for that statement.
By 2022, Newbury Park had won three consecutive national championships.
Brosnan’s book documenting how this happened, Beyond Fast: How a Renegade Coach and His Unlikely High School Team Revolutionized Distance Running (co-written with Chris Lear and Andrew Greif, published 2025), has pulled back the curtain on a training system that most coaches have heard about and few have fully understood. This article breaks down what Brosnan actually does, why it works, and how you can begin applying the principles to your own program.
Why This Dynasty Matters to You
The easy response to Newbury Park is to assume it happened because of California talent pools, weather advantages, and resources that most programs do not have. Those factors exist. They do not explain what Brosnan built.
Talent pools do not explain a program that was irrelevant for 25 years before a coach arrived and changed everything. Weather does not explain the specific training choices Brosnan made that contradict what most coaches do. Resources matter, but Sean Brosnan did not invent the altitude camp or the double session. He made specific, documented decisions about how to structure training, and those decisions are replicable in principle by any coach willing to examine their assumptions.
The Newbury Park system challenges three things most coaches believe without questioning: that base training should be slow, that the 7-day week is the natural training cycle, and that mileage accumulation is the primary development driver in high school cross country.
The Background: Building From Zero
Brosnan arrived at Newbury Park from a coaching background that included formative time in Portland, Oregon, where he was exposed to Alberto Salazar and Jerry Schumacher’s training approaches. Both coaches operated at the professional level with systems built around continuous quality development and the progressive repetition of similar workouts over time. Neither believed in strict periodization that removed entire energy systems from training for months at a time.
Brosnan brought this philosophy to a high school program starting from nothing and declared an aggressive timeline. The declaration was not marketing. It was a coaching philosophy made public. If you are telling your athletes and parents you will win a state title in four years, you are committing to a development arc rather than a reactive coaching approach. You are saying: I know what this program needs, I know how to build it, and the timeline is four years, not four months.
Athletes and families responded. The culture formed around that shared belief. The training system had something to work with.
The Training System Breakdown
Mileage: Quality Over Volume
Brosnan has been asked repeatedly about the mileage his athletes run. The numbers consistently surprise coaches who assume national champions require 70-80-mile summer builds.
His top athletes reach 60-70 miles per week by senior year. Colin Sahlman, who set national high school records under Brosnan, trained under 60 miles per week throughout his career. The highest single-week mileage ever logged by any athlete in the program: 64 miles.
The highest mileage weeks come in October, during the competitive cross country season, not during summer base building. This is the opposite of what most programs do.
The summer is not a mileage accumulation period for Brosnan. It is the period when athletes build toward the quality that October demands. Mileage builds to a point and then stays there. Quality is what advances.
The 10-Day Training Cycle
This is the structural innovation that most coaches who study Brosnan focus on, and for good reason. He does not train in 7-day weeks.
His training runs on a 10-day cycle. The long run occurs every 10 days rather than every 7. Quality sessions are distributed within the 10-day structure rather than forced into the 7-day calendar that every coach inherits from the athletic week.
The practical effect is significant. A 7-day week forces a hard workout on day six because that is what the schedule says, regardless of whether the athlete has recovered from day three’s workout. A 10-day cycle allows the coach to prescribe training based on actual recovery rather than the calendar. Athletes are not dragged into quality sessions before the adaptation from the last quality session has occurred.
Elite athletes in the program also ran doubles three times per week: a morning shakeout session followed by an evening supplemental training session. One complete rest day was preserved per 10-day cycle.
Conjugate Periodization: All Systems, All Year
The biggest conceptual departure from standard high school cross country coaching is Brosnan’s rejection of periodization as most coaches practice it.
Traditional periodization in high school XC looks like this: summer is base phase (long slow distance, no fast running), September-October is build phase (tempo work begins, race-specific fitness develops), November is peak phase (workouts go sharp, mileage drops). Each phase has a primary focus and the other systems are suppressed.
Brosnan runs a conjugate model: every energy system receives training stimulus at all times of year. The ratios shift. Speed work is a smaller percentage of training volume in July than in October. But it is never removed.
His exact words on the conventional base phase: “I always hate the word base phase. I like to do everything year-round, and to me it’s all progression.”
The practical implementation: athletes run 1000-meter repeats beginning in July. In July, those repeats are run at 2:56 per repeat. By November, the same workout structure is run at 2:46 per repeat. The progression over 16 weeks is a 10-second-per-repeat improvement. The workout has not changed. The fitness has.
This approach mirrors Salazar and Schumacher’s philosophy directly: repeat the same workouts and progress them. Do not cycle through entirely different training stimuli and hope the body integrates everything at championship time.
Surface: Soft Surfaces as Non-Negotiable
Brosnan banned concrete from his athletes’ training surfaces. This is not a general preference. It is a structural decision with logistical consequences.
The program used volunteer drivers to transport athletes to appropriate soft-surface training locations. When the coach values the decision highly enough to build logistics around it, the athletes understand it is serious. Concrete stress fractures did not disrupt the Newbury Park dynasty because the training environment did not allow concrete running.
Supporting this, the program built hip and glute strengthening and ankle mobility work into the structural core of training, not as optional supplemental work. Injury prevention was not an afterthought. It was designed into the training week.
Altitude Camps
Regular periods of training at Big Bear Lake, California (7,000 feet elevation) created hematological adaptations that supplement the training load. Monthly camp exposure, even for short periods, contributes to red blood cell volume, aerobic capacity, and, perhaps as importantly, the psychological effect of a training environment separate from the daily school routine.
The Philosophy Behind It
The Brosnan philosophy can be reduced to one principle: touch every system continuously and progress the quality of each.
Most coaches are afraid to run fast in base phase because they believe fast running requires more recovery than slow running and will interrupt the aerobic development they are trying to build. Brosnan argues this is only true if the fast running is poorly designed. Short, controlled speed development work that does not generate significant lactate does not compromise aerobic training. It maintains the neuromuscular patterns that make fast running possible.
“I always like to do everything year-round,” he has said. “I don’t set boundaries. We really don’t. We just go after what we want.”
That last sentence is important. It was said to high school athletes who had no reason to believe their program would win anything. The coach’s belief in what the athletes were capable of preceded any evidence that they were capable of it. Brosnan was coaching culture and training simultaneously. They were inseparable.
What Most Coaches Get Wrong
The typical high school cross country program runs slow all summer, adds tempo work in September, and wonders why the athletes who look great in October fall apart at championships in November. The answer is almost always the same: the speed was introduced too late, the mileage peak came too early, and the athletes arrived at championships slightly fatigued rather than sharply fit.
Brosnan’s system inverts this. Speed is present from July. The mileage peak is in October, not August. Athletes arrive at championships having run their hardest, fastest work in the four weeks before the meet, not six weeks before.
The specific failure mode I see most often in high school programs is the early-season mileage spike. Coaches are excited in July, athletes are fresh, and the temptation is to build fast. Then September arrives and athletes are carrying fatigue from an August mileage peak. The workouts suffer, confidence drops, and coaches try to solve a training problem with more training. The Brosnan model says plan the peak for when it matters, not for when you are most motivated to train.
How to Apply This to Your Program
You do not need to recreate the full Newbury Park system tomorrow. These are the elements that transfer most directly to a standard high school program with standard constraints.
1. Try a 10-day cycle for one training block.
Take your August block and run it on a 10-day structure. Schedule quality sessions and long runs based on recovery rather than day of week. At the end of the block, ask whether your athletes showed up to quality sessions fresher than they typically do. If yes, consider adopting the structure permanently.
2. Add one speed development session per week in your summer base plan.
This does not need to be a structured workout. After an easy run, add 6 to 8 repetitions of 100 meters at controlled effort, between 90 and 95 percent, with full recovery between each. This session takes fifteen minutes. It maintains the neuromuscular qualities that will make October workouts more effective. A summer of two-a-week strides plus one 100-meter speed development session produces a different athlete in September than a summer of only slow running.
3. Set a mileage ceiling based on your athletes’ current training history, not a target.
Brosnan’s 64-mile ceiling was not arbitrary. It was the upper limit where his athletes could train and recover without injury. Most high school coaches set mileage targets and push athletes toward them regardless of whether recovery is occurring. Set the ceiling at 10 percent above where your athletes currently train sustainably and do not exceed it. Progress the quality inside that ceiling.
4. Eliminate concrete from at least 50 percent of your training surfaces.
You may not have volunteer drivers. You almost certainly have a grass field, a trail, or a gravel path within reasonable distance of your training grounds. Make one easy run per week a deliberate soft-surface run. Track the injury rates in your program over two seasons. The data will be persuasive.
5. Tell your athletes where this is going.
Brosnan told his athletes they would win a state title in four years. You can adapt this. Tell your incoming freshmen what you are building. Tell them the process. Tell them what the four-year commitment looks like. Athletes who understand the purpose of their training perform it differently than athletes following instructions they do not understand.
The Bottom Line
Newbury Park was not always great. It was invisible for 25 years. Then a coach arrived who had thought carefully about what the training should look like, told everyone the goal out loud, and built a system designed to reach that goal over four years.
The system had specific, learnable elements: a 10-day cycle, year-round speed work, a mileage ceiling rather than a mileage target, soft surfaces as a requirement, and the progressive repetition of quality sessions across the full training year.
Three national championships later, the system is documented. The question is whether you are willing to challenge the assumptions that are producing whatever results your program is currently getting.
The 24-week training system that takes your athletes from June through November is laid out in full at the High School Cross Country Training: The Championship Blueprint. If Brosnan’s approach to periodization changed how you think about the training year, the Blueprint is the week-by-week architecture that applies those principles to your season.
