New Study Finds Splitting Strength and Conditioning Days May Double Progress for Functional Athletes

A new study launching April 7 may reshape how thousands of functional athletes train.

Led by Wod Science and senior exercise physiologist Gar Bennet, the “Hybrid 2.0” project is a direct response to one of the most hotly debated topics in fitness science: Does training strength and conditioning together compromise performance?

The new study builds on last year’s findings that showed participants gained fitness twice as fast when they separated strength and endurance workouts by an entire week. Now, the research team is testing a more realistic structure—alternating training days instead of alternating training weeks.

“We learned a lot from the feedback we received after Hybrid 1.0,” said Bennet, based in Zurich, Switzerland. “This time, we’re not only tightening up the testing, we’re designing the protocol to be more practical for everyday athletes and coaches to implement.”

The 10-week study is open to public participation and aims to provide actionable insight for CrossFitters, hybrid athletes, and the broader functional fitness community.

The New Study at a Glance

The Hybrid 2.0 project is designed to directly compare two distinct training setups over a 10-week period:

• Group A: Strength training followed immediately by a metcon or endurance session — mimicking how most CrossFit programs are structured.
• Group B: Strength training and conditioning split across alternating days — with no sessions combining both in a single workout.

“Both groups do exactly the same training,” said Bennet. “Same lifts, same metcons, same volume — the only difference is when they do them. One group stacks strength and endurance, the other separates them by 24 hours.”

The researchers hope this tweak in structure can maintain the performance benefits seen in their previous study, while offering a more accessible method for everyday athletes and coaches.

What Is Concurrent Training — and Why Is It So Controversial?

Concurrent training refers to combining two or more training modalities in a single session — such as lifting heavy back squats and then jumping straight into a high-intensity conditioning workout.

While common in CrossFit, HIIT bootcamps, and even team sports, the science behind it is complex.

Decades of research suggest a potential “interference effect” — where endurance training may blunt muscle growth or strength gains, and vice versa.

A 2021 meta-analysis showed that while combining strength and cardio doesn’t reduce endurance gains, it can diminish hypertrophy compared to strength-only protocols.

“The key question isn’t if concurrent training works,” said Bennet. “It’s how to structure it to minimize the trade-offs — especially for athletes who need to develop both strength and conditioning at a high level.”

This dilemma is especially relevant for athletes in hybrid sports like CrossFit and Hyrox, where competition demands high output across multiple energy systems.

Hybrid 1.0: The Original Study That Sparked Debate

In 2023, Wod Science conducted a novel remote study involving over 100 CrossFit athletes worldwide.

Participants were split into two groups:

• Group A followed what Bennet called a “commercial CrossFit” model — 4 weekly sessions combining strength and metcons.
• Group B used an extreme separation approach — one full week of strength-only, followed by one week of conditioning-only, repeating for 8 weeks.

Despite skepticism, the results were striking.

• Group A improved performance by 7.8%
• Group B improved by 15% — nearly double the gains

The improvement was statistically significant and consistent across multiple tests, including:

• CrossFit Total (squat, press, deadlift 1RMs)
• Fran (thruster-pull-up benchmark WOD)
• 2K Row
• Clean & Jerk 1RM
• Bodyweight back squat AMRAP

“We were surprised by how clearly the separated group outperformed the traditional model,” said Bennet. “But we also realized that separating training by a full week is probably not realistic for most people.”

That realization — paired with a flood of community feedback — led directly to the launch of Hybrid 2.0.

Valid Critiques Prompt Study Redesign

Bennet says the first study taught his team a lot — not just from the data, but from the community response.

Three primary critiques stood out:

1. Confusing Terminology

Calling the first group “traditional CrossFit” sparked backlash.

Many athletes pointed out that CrossFit HQ methodology doesn’t require combining strength and metcons. In fact, HQ often programs single-modality days.

“It’s a fair point,” said Bennet. “But from my personal experience — 14 years of training in affiliates — most programs do structure sessions with strength followed by a workout. And big platforms like HWPO and Proven program this way too.”

He’s right. A review of HWPO’s and Proven’s current programming reveals a clear pattern: strength work first, followed by a metcon.

2. Biased Testing

Most of the Hybrid 1.0 tests were squat- or strength-heavy, such as CrossFit Total, Clean & Jerk, and bodyweight back squat AMRAP.

Critics argued that this favored the strength-focused weeks and didn’t reflect the broader demands of CrossFit, such as gymnastics volume or longer metcons.

“Looking back, we probably over-indexed on strength tests,” said Bennet. “We based it on data showing squat strength correlates best with Open performance — but we’re definitely fixing that for Hybrid 2.0.”

3. Real-Life Applicability

Some called the weekly separation impractical.

“I get it,” Bennet admitted. “Training strength one week and only conditioning the next isn’t how most people train. But guess what? We launched a program based on it, and people are still following it six months later. So maybe it’s not that crazy.”

Still, Hybrid 2.0 shifts to a more realistic model: one day strength, one day conditioning — repeat.

What Makes Hybrid 2.0 Different

This time, the separation isn’t radical — it’s one day, not seven.

Both groups still do the same:

• Compound lifts (e.g. squats, presses, Olympic lifts)
• Conditioning pieces (e.g. metcons, intervals, rows)
• Volume and intensity

The only variable: timing.

“That’s why this study is so important,” said Bennet. “If separating by just one day leads to better results, it gives coaches and athletes a tool they can actually use in the real world.”

Participants are being recruited via the STVY platform. To be eligible, they must:

• Complete pre- and post-tests
• Follow 80% of the training plan
• Train remotely and log results accurately

All participants receive 10 weeks of free programming.

Crowdsourcing the Ideal Test Week

Another innovation in this study: community involvement in designing the tests.

Bennet is actively inviting coaches and athletes to suggest test workouts via social media, asking for:

• Strength tests that reflect general athleticism
• Endurance tests beyond just rowing or assault bike
• Metcons that mimic Open-style workouts (12–20 minutes)
• Skill ladders to capture gymnastic proficiency (e.g., pull-up → chest-to-bar → bar muscle-up)

“We’ve got five days to test everything — strength, metcon, endurance, skills — without completely wrecking people,” he said. “If you’ve got ideas, send them.”

Why This Research Model Is Unique

Wod Science is pioneering a new way of doing exercise science — open-source, transparent, and athlete-driven.

Instead of publishing behind paywalls, Bennet shares everything via YouTube, Instagram, and community platforms — inviting real-time feedback and continuous iteration.

“When you publish in a journal, you might get two peer reviews,” said Bennet. “When you post on Instagram, you get hundreds. Some are harsh, but many are smart — and they make our work better.”

That level of transparency is rare in sports science, and it’s helping generate data that’s directly applicable to functional athletes around the world.

How to Join or Follow the Project

Interested athletes can still sign up for the Hybrid 2.0 study through STVY, and the team is particularly encouraging participation from:

• Everyday CrossFitters
• Hybrid athletes training for events like Hyrox or Tactical Games
• Coaches curious about optimizing programming structure

Participants get:

• 10 weeks of high-quality programming
• Involvement in cutting-edge sports science
• A chance to shape future performance training methods

Final Thoughts

Hybrid 2.0 could provide some of the clearest data to date on how to best structure strength and conditioning for functional athletes.

If separating sessions by just one day boosts results, it could rewrite the playbook for fitness programming — from elite coaching platforms to everyday gym-goers.

“We’re not trying to push a dogma,” said Bennet. “We just want to give people better tools to get better results — and the data to back it up.”

The study launches April 7. The findings could shift how the entire functional fitness community trains in 2025 and beyond.

Source: New Study Finds Splitting Strength and Conditioning Days May Double Progress for Functional Athletes