A quick scan of what happened.

• Lionel Sanders and Jackie Hering Win the Inaugural IRONMAN 70.3 Dallas–Little Elm — Bad weather forced organizers to shorten the pro swim to 350 meters and cancel the age-group swim entirely, though World Championship qualifying slots were still awarded. Sanders thrived in the chaos — he entered T2 as the fastest on the bike and held on to win, extending his season-opening streak to three consecutive victories. American Jackie Hering took the women's title in dramatic fashion, overtaking Germany's Anna Buettner in the closing meters.

• James Sprague and Lucy Campbell Win Wodapalooza — Sprague dominated the men's individual competition, winning three of the five events to finish with 364 points. Campbell took the women's crown with 354 points, edging out Estonia's Andra Moistus. Sunday's team events were cancelled due to severe weather and lightning, capping off a weekend that was plagued by bad conditions in Miami Beach from start to finish. The weekend also served as the stage for the CrossFit Open 26.3 announcement, with Olivia Kerstetter winning the live throwdown.

• HYROX Releases Expanded North America Fall Schedule — HYROX dropped its fall 2026 North America calendar this week, adding Tampa, Denver, Nashville, and Salt Lake City to the schedule for the first time. Release dates for tickets have yet to be announced. Full fall schedule below 👇

If you are having trouble building muscle, it’s likely that you’re making one or two key mistakes that are holding you back. The good news is that the science is clear on what actually drives muscle growth — and it's more flexible than most people think.

What Hypertrophy Is

Hypertrophy is the process of increasing muscle size through resistance training. It's triggered primarily by mechanical tension — the force your muscles produce against a load — and it happens when your body is consistently building more muscle protein than it's breaking down. However, in order for hypertrophy to be triggered, you need to reach the right balance of fatigue and volume.

Rep Ranges

The traditional 8–12 rep range is a useful starting point, but research shows hypertrophy can occur anywhere from 3 to 30 reps. The key variable isn't the rep count itself — it's proximity to failure. As long as you're taking sets close to failure, the muscle is being sufficiently challenged to grow, whether that's heavy sets of 4 or lighter sets of 20.

Think about this as you work through your next lift. If the program prescribes a certain number of reps, make sure you’re using a weight that challenges you. And if it doesn’t, then add on more reps to make sure you’re not leaving too much in the tank.

The ability to reach hypertrophy through different rep ranges is also good news for hybrid athletes. It means you're not locked into a specific rep range and can adapt your loading based on where you are in your training cycle.

How Many Sets Per Week

Volume — measured in hard sets per muscle group per week — is the primary driver of hypertrophy. The necessary volume to trigger growth varies by muscle group.

For larger muscle groups like the chest, back, and quads, the evidence supports 10–20 direct sets per week as the effective range. A practical target for most trained hybrid athletes is 10–15 total sets for chest (think bench press, dumbbell press, and fly variations), 12–15 sets for back (rows, pulldowns, pull-ups), and 12–16 sets for legs — though note that your quads may already be taking a significant indirect stimulus from running, which counts for something.

Smaller muscle groups need less total volume to grow. Research supports 6–10 direct sets per week for biceps, triceps, shoulders, hamstrings, and calves. Your arms in particular get meaningful indirect work from pressing (triceps) and pulling (biceps) movements, so dedicated isolation work can sit at the lower end of that range and still produce results. The triceps is one exception worth noting — research specifically shows it responds better to higher volumes than other smaller muscle groups, so pushing toward 10 sets per week there makes sense.

The other key finding is that spreading sets across 2–3 sessions per week produces better growth than cramming them into one. Hitting your chest with 6 sets on Monday and 6 sets on Thursday will outperform 12 sets in a single session.

Applying This to Hybrid Training

A few principles that translate well into a hybrid program:

Consolidate stress. Stack hard strength sessions on the same days as hard running sessions where possible. This concentrates fatigue into fewer days and leaves the remaining days genuinely easy — which is when recovery and adaptation happen.

Prioritize mechanical tension in lengthened positions. Loading muscles at longer muscle lengths — Romanian deadlifts, deficit lunges, incline curls — produces a strong hypertrophic stimulus and is more joint-friendly during high run volume phases when your legs are already under load.

Lower reps during high endurance phases. When weekly mileage is high, 3–5 rep ranges at moderate loads let you maintain the mechanical tension stimulus without piling additional fatigue onto already-taxed lower body tissue. Save higher-rep, higher-volume work for base-building phases when run intensity is lower.

The Bottom Line

The single most useful habit you can build when trying to gain muscle is tracking your weekly sets per muscle group. It's easy to feel like you're doing enough strength work when you're actually falling short of the stimulus required to drive growth. Write it down, count it weekly, and make sure you're consistently hitting your targets — at an effort level close enough to failure to actually count.

RPE Quick Reference

For Lifts: RPE 5–6 — Moderate effort. Several reps left in the tank. RPE 7 — Challenging but controlled. This is the default working effort. RPE 8 — Hard. You could do more, but quality would slip. RPE 9 — Very hard. ~1 rep left. Near max for the day. RPE 10 — Max effort. Nothing left.

For Runs: RPE 4–5 = conversational Zone 2. RPE 6–7 = threshold, hard to hold a sentence. RPE 8–9 = race effort.

If you found this useful, forward to your training partners.

Train Hybrid,