Conquering Downhills in Ultramarathons: Strengthening Your Quads Using the Repeated Bout Effect

"My quads are absolutely ruined!" If I had a penny for every time I've heard (or said) this post-ultra, I'd be a wealthy man.

You probably know the feeling all too well: waking up the next day, staring bleakly at your staircase, knowing the descent is going to be a painful shuffle supported by the handrail—and a lot of swearing under your breath.

While sore quads might feel like a badge of honour, extreme cases can even escalate to a condition called Rhabdomyolysis—serious stuff that we'll get into shortly.

But here's the good news: there's a scientifically proven strategy called the Repeated Bout Effect (RBE) to help fortify your quads, ensuring you're better prepared for the pounding of ultramarathon descents.

Understanding the Repeated Bout Effect

The RBE is essentially your muscles' brilliant capacity to learn and adapt from prior stress. Every time you descend steep terrain, your quads engage in eccentric contractions, meaning they lengthen under load to absorb shock. This eccentric loading causes micro-damage to the muscles, leading to soreness and fatigue.

However, after this initial bout of soreness, your muscles adapt and become tougher, reducing muscle damage significantly during future downhill efforts. These protective adaptations include:

• Structural Changes: Muscle fibers strengthen and connective tissues become tougher.
• Neural Improvements: Enhanced coordination and better distribution of workload across muscle fibers.
• Cellular Benefits: Less inflammation and faster muscle repair processes.

Strategically applying these principles—rather than the common misconception of "just run downhills more often"—is key to effectively harnessing RBE.

Recognizing and Preventing Rhabdomyolysis

Before diving deeper, let's touch on Rhabdomyolysis—a rare but potentially dangerous condition resulting from severe muscle breakdown. This condition occurs when damaged muscles release a protein called myoglobin into your bloodstream, potentially harming your kidneys. Symptoms include:

• Severe muscle soreness and swelling
• Significant weakness or fatigue
• Dark, cola-colored urine

Typically, this condition arises from excessively aggressive or poorly planned downhill training. It's essential to be aware and proactive: if something doesn't feel right, don't push through. Rest, hydrate thoroughly, and seek medical attention if symptoms persist.

Practical Training Guide for Harnessing RBE

Here's a detailed, step-by-step guide you can immediately incorporate into your training routine:

1. Optimal Frequency and Timing

Plan specific downhill sessions approximately every 2-3 weeks to foster muscular adaptation without risking overtraining. Schedule your most significant downhill sessions about 3-5 weeks prior to your race, allowing sufficient recovery while retaining adaptations.

2. Structured Progressive Overload

Gradually introduce more demanding downhill efforts:

Weeks 1-4:

• Short, moderate descents (5-10 mins, slopes around 4-6%) at an easy pace.
• Total weekly downhill running: approximately 15-20 minutes.

Weeks 5-8:

• Increase segment length (10-20 mins) and gradient (6-10%), maintaining controlled effort.
• Total weekly downhill running: approximately 25-30 minutes.

Weeks 9-12:

• Further extend downhill segments (20-30 mins) with slopes of 8-12%, and begin adding faster-paced intervals.
• Total weekly downhill running: approximately 30-40 minutes.

Weeks 13-16 (Race Preparation Phase):

• Perform 1-2 key long runs simulating race-specific downhill conditions.
• Maintain downhill elements during your taper phase but significantly reduce volume and intensity.

3. Integrating Downhill Running into Long Runs

Use your regular long runs to strategically include downhill segments:

• Maintain a steady, purposeful downhill effort rather than a leisurely pace.
• Example: In a 3-hour trail run, intentionally run downhill segments of about 15-20 mins at controlled intensity.

4. Targeted Downhill Sessions (Every 2-3 Weeks)

• Downhill Tempo Runs: 20-30 minutes of continuous downhill at comfortably challenging intensity.
• Downhill Intervals: 3-5 repetitions of 5-8 minutes descending at a higher intensity, with relaxed uphill recovery intervals.
• Race Simulation Runs: Execute one major session replicating key downhill segments from your goal race, ideally within 3-5 weeks of race day.

Staying Alert for Signs of Overtraining

Always listen to your body and look out for these critical warning signs:

• Persistent muscle soreness beyond three days.
• Unusual fatigue or declining performance.
• Joint or tendon pain, particularly around the knees or Achilles.
• Symptoms indicative of rhabdomyolysis (intense pain, swelling, or dark urine).

If you notice these symptoms, back off immediately, increase recovery time, hydrate, and seek medical advice if issues persist.

Nutrition and Recovery Strategies

To maximize your training adaptations, pay close attention to your nutrition and recovery habits:

• Protein Intake: Target between 1.6-2.2g/kg bodyweight daily for optimal muscle repair.
• Anti-inflammatory Nutrition: Regularly consume foods rich in omega-3s and antioxidants (e.g., salmon, berries, leafy greens).
• Hydration & Electrolyte Management: Consistent fluid intake and balanced electrolyte supplementation.
• Active Recovery Practices: Engage in gentle recovery activities (walking, cycling), use compression gear, practice mobility exercises, and prioritize sleep!

Bringing It All Together

The Repeated Bout Effect isn't merely academic jargon—it's a proven pathway to more resilient quads, faster recovery, and improved race performance. I've personally experienced these benefits—most notably at CCC by UTMB, where, despite other setbacks, my legs felt robust and fresh deep into the race. Even more telling was how quickly I recovered, knocking out a solid 1:22 half marathon just a week later!

Incorporate these methods thoughtfully into your own training, and rather than dreading descents, you'll confidently tackle them head-on—no longer fearing your staircase in the days following your next ultra!

Keep training smart, stay healthy, and see you out on the trails!

‍

References:

Bontemps B, Vercruyssen F, Gruet M, Louis J. Downhill Running: What Are The Effects and How Can We Adapt? A Narrative Review. Sports Med. 2020 Dec;50(12):2083-2110. doi: 10.1007/s40279-020-01355-z. PMID: 33037592; PMCID: PMC7674385.

Tallis J, McMorrow C, Shelley SP, Eustace SJ. Repeated Bout Effect of Downhill Running on Physiological Markers of Effort and Post Exercise Perception of Soreness in Trained Female Distance Runners. Sports (Basel). 2024 Jun 17;12(6):169. doi: 10.3390/sports12060169. PMID: 38921863; PMCID: PMC11209549.

Tallis J, McMorrow C, Shelley SP, Eustace SJ. Repeated Bout Effect of Downhill Running on Physiological Markers of Effort and Post Exercise Perception of Soreness in Trained Female Distance Runners. Sports (Basel). 2024 Jun 17;12(6):169. doi: 10.3390/sports12060169. PMID: 38921863; PMCID: PMC11209549.