You’ve been crushing your lifting PRs for months, then decide to add running to your routine. Suddenly, your squat feels heavier, your bench press stalls, and you’re convinced you’re losing all your hard-earned strength. Or maybe you’re a dedicated runner who starts lifting, only to watch your pace slow and your legs feel like concrete on your usual routes.
Before you panic and abandon your hybrid training goals, let me tell you something crucial: this temporary performance decrease is completely normal and expected when you start concurrent training.
Today I’m breaking down why this happens, how long it lasts, and most importantly – why you need to stick with it through the “suck window” to see the real benefits of hybrid training.
Hybrid training, also called concurrent training, is simply mixing strength and endurance training within the same training week, month, or block. This could look like:
This approach mirrors how general athletes train and is becoming increasingly popular among fitness enthusiasts who want to be well-rounded rather than specialized in just one area.
When you add a new training modality to your routine, you’ll likely experience:
This isn’t your imagination, and it doesn’t mean you’re doing something wrong. This is your body’s normal response to managing multiple training stressors simultaneously.
There are several physiological reasons why your performance temporarily decreases when you start hybrid training:
Your body only has so much capacity to recover from training stress. When you add a new modality, you’re asking your recovery systems to work overtime without necessarily increasing your recovery resources.
New types of training are inherently more fatiguing than familiar patterns. Your body is working harder to adapt to unfamiliar movement patterns and energy system demands.
Both strength and endurance training tax your central nervous system, but in different ways. When you combine them, there can be interference between adaptations, leading to temporary decreases in performance in both areas.
Simply put, you’re doing more work. Your body needs time to adapt to the increased caloric and nutritional demands of training multiple systems.
Here’s the crucial distinction: temporary performance decreases due to fatigue are not the same as fitness loss. You’re still making adaptations and gaining fitness in both areas – you’re just experiencing the normal fatigue that comes with increased training load.
Think of it like this: if you’ve been training for a powerlifting meet and adding volume leading up to your peak, you expect to feel fatigued. But when you taper and recover, you often hit PRs because you were building fitness all along – it was just masked by fatigue.
The same principle applies to hybrid training. You might feel slower or weaker in the short term, but you’re actually building a broader, more robust fitness base.
The “suck window” typically lasts 6-12 weeks, depending on several factors:
Remember, adaptation isn’t a one or two-week process. Real physiological changes take time – often months to fully manifest.
Rather than rigidly sticking to prescribed weights or paces, use Rate of Perceived Exertion (RPE) to auto-regulate your training intensity. This allows you to still provide appropriate training stimulus even when you’re more fatigued.
For your endurance training, use my free heart rate zones calculator to ensure you’re training at appropriate intensities rather than getting caught up in pace frustrations.
You’re asking more of your body, so you need to give more back. Focus on:
Consider spending focused seasons developing the area you’re weaker in while maintaining (rather than maximizing) your stronger area. This reduces the ego blow of seeing performance drops while you’re actively trying to peak in both areas.
Your athletic background significantly impacts how you’ll respond to hybrid training:
If you have years of solid lifting or running experience, you can typically maintain that fitness more easily while adding the new modality. Maintaining fitness is much easier than building it from scratch.
If you’re relatively new to both strength and endurance training, you might actually see improvements in both areas simultaneously – the “beginner gains” effect. However, you’ll need to be more conservative with volume to allow for proper recovery.
If you’re building both from the ground up, expect the adaptation period to take longer. You might benefit from focusing on one area at a time initially, then gradually combining them as your fitness base improves.
Your body’s energy demands increase significantly when you start concurrent training. Poor nutrition can exacerbate the performance drop and extend the adaptation period. My Fast and Fed Guide provides specific strategies for fueling hybrid training, including carb timing around different types of sessions.
I like to think of training capacity like a fishbowl. When you start hybrid training, your “fishbowl” (recovery capacity) might be relatively small. As you adapt over time, your fishbowl gets bigger, allowing you to handle more volume in both areas without the same performance interference.
The goal isn’t to force more water into a small bowl – it’s to gradually expand the bowl’s capacity over months and years of smart training.
While temporary performance drops are normal, watch out for:
These might indicate you need to reassess your training volume, recovery practices, or overall approach.
If you’re ready to start or optimize your hybrid training approach, The Lyss Method programs provide structured lifting and running plans designed to complement each other, taking the guesswork out of how to combine these training modalities effectively.
For additional support in your hybrid training journey:
That temporary dip in performance when you start hybrid training? It’s not a sign you should quit – it’s a sign your body is adapting to new demands. This is exactly what should happen when you challenge your fitness in new ways.
The key is leaving your ego at the door and trusting the process. Focus on consistent effort rather than specific numbers. Use tools like RPE and heart rate zones to ensure you’re still providing appropriate training stimulus even when the weights feel heavier or the pace feels slower.
Remember: you’re not losing fitness in the short term – you’re building a broader, more resilient fitness base for the long term. Sometimes moving forward in two areas at once means temporarily holding position in one while you develop the other.
Give yourself 6-12 weeks to adapt. Be patient. Be consistent. And most importantly, be kind to yourself during the process. The performance will come back, and when it does, you’ll be stronger and more well-rounded than ever before.
Keywords: hybrid training performance drop, concurrent training effects, combining lifting and cardio, strength and endurance training, why performance decreases hybrid training, adaptation period concurrent training, RPE training fatigue, central nervous system interference training
I’m Exercise Physiologist, sports nutritionist, weight lifter, and ultra runner. I am here to bring science to your training in a no-nonsense way. I have helped thousands of women crush big lifting goals, cross race finish lines, and even do both. I’m here to help you do the same!
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