We Tested the SkiErg, Rower, and Assault Bike. Only One Delivered the Best Conditioning Return

Cardio machines are a lot like dogs. Some are loyal companions you’ll love forever. Others? They’ll chase you down and leave you gasping for air. Few tools in the gym spark more debate than the SkiErg, the rower, and the Assault Bike. Each promises a full-body beatdown and next-level conditioning, but which one deserves the title of man’s best friend?

To find out, we tapped Vincent DiPrimio, BS in exercise science, CSCS, and hybrid performance coach. He programs all three machines regularly for athletes and everyday clients, so he knows exactly where each one shines and which causes more suffering than it's worth.

“The best machine often comes down to how it fits your body, your goals, and your ability to stay consistent,” says DiPrimio. With that in mind, let’s break down the physiology, training benefits, and common pitfalls of the SkiErg, rower, and Assault Bike and see how they stack up head-to-head.

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Meet the Machines

Before we crown a champion, it’s worth understanding what each machine brings to the table. The SkiErg, rower, and Assault Bike all deliver punishing workouts, but the way they recruit muscle, tax your lungs, and demand technique couldn’t be more different. Some torch the upper body, others hammer the legs, and a couple put your entire system through the wringer. As DiPrimio explains, the right fit often comes down to knowing exactly what each tool does best and how it might break you down if you’re not careful.

What to Know About the SkiErg

Originally designed to mimic the demands of Nordic skiing, the SkiErg is a vertical pull machine from Concept2 that torches the upper body and core while sparing the legs.

Before You Hop On

New users often underestimate how much this machine taxes the triceps, lats, and abs. “You’ll feel smoked in your upper body the first time you use it,” DiPrimio warns. His advice: build up volume slowly before trying brutal HIIT sessions.

How to Use It

Common form mistakes like squatting before hinging and keeping your arms too straight through the pull show up quickly on the SkiErg. DiPrimio advises hinging before squatting and pulling with bent arms for stronger strokes and faster cycle times.

Muscular Recruitment

According to DiPrimio, the SkiErg targets your arms, shoulders, pecs, lats, and anterior core, with a small contribution from the lower body. That makes it unique compared to the rower and Assault Bike. “It’s the best of the three if you’re looking to condition your upper body without hammering your legs,” he says.

Cardiovascular Demand

While the SkiErg can deliver a serious sweat, it ranks a notch lower than the rower or bike in terms of pure cardio demand. Since it engages less overall musculature, VO2 max numbers and lactate levels won’t climb as high. “You’ll feel it more in your arms, lats, and abs than in your lungs,” notes DiPrimio.

What to Know About the Rower

The rower is the workhorse of conditioning equipment. Concept2 models have been the gold standard for decades, found everywhere from college boathouses to CrossFit gyms. Each stroke demands coordination, power, and rhythm, and rewards you with one of the most complete workouts you can get in the gym.

Before You Hop On

Breathing rhythm can feel awkward for beginners. Unlike running or cycling, rowing’s stroke cycle is less intuitive. “Finding the right breathing rate is crucial,” says DiPrimio. He recommends experimenting with different rhythms for steady-state versus intervals until you discover the pattern that helps you stay efficient under fatigue.

How to Use It

Technique can make or break your rowing session. DiPrimio highlights a few common mistakes:

• Failing to keep the shins vertical at the catch.
• Overusing the back instead of driving first with the legs.
• Pulling with the arms too early in the stroke.
• Rushing recovery and bending the knees before the arms and torso reset.

Correcting these flaws not only prevents injury but also makes rowing far more sustainable for longer sessions.

Muscular Recruitment

“The rower recruits the most muscle of all three machines,” says DiPrimio. Every stroke drives from the legs, transfers through the hips and core, and finishes with the upper back and arms. You’ll light up your quads, glutes, hamstrings, lats, biceps, and core in a single rep. That’s why DiPrimio calls it the most full-body option of the bunch.

Cardiovascular Demand

Due to the extensive range of motion and the amount of musculature involved, rowing generates a significant calorie burn and a substantial cardiovascular demand. VO2 max, lactate production, and EPOC numbers all climb higher on the rower than the SkiErg, and DiPrimio points out that it matches the Assault Bike in overall conditioning effect. “For a long steady grind or intervals, the rower is incredibly efficient,” he explains.

What to Know About the Assault Bike

The Assault Bike, also known as the air bike, is as straightforward as it gets: pedal with your legs while moving the handles back and forth with your arms. The fan-based resistance means the harder you push, the harder it pushes back. That simple design makes it one of the most brutal conditioning tools in the gym.

Before You Hop On

The bike is notorious for producing massive lactate spikes. “It has a way of humbling people fast,” says DiPrimio. Even experienced athletes are often caught off guard by how quickly their legs and lungs shut down. Respect the bike, or it will ruin your day.

How to Use It

The most common mistake isn’t about form, it’s about pacing. Athletes explode out of the gate only to crash and burn within minutes. DiPrimio’s advice: start conservatively and build your effort. Treat it like a marathon, not a sprint; unless you’re doing actual sprints.

Muscular Recruitment

“The bike hits your legs hard, but it’s also a push-pull machine for the upper body,” says DiPrimio. Expect your quads, hamstrings, glutes, chest, shoulders, triceps, and back to get in on the action. Combined with the core, it creates a global demand that rivals the rower.

Cardiovascular Demand

In lab settings, the Assault Bike shows higher perceived exertion and lactate levels than the SkiErg or rower because there’s no real recovery phase as you’re working every second of the stroke. “It’s easy to feel fine for the first interval and then absolutely wrecked by the end,” DiPrimio says. This drastic spike in intensity is why the assault bike is a favorite for short, savage intervals.

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Head-to-Head Comparison

Now that we’ve met the contenders, it’s time to see how they stack up side by side. Each machine has its strengths, weaknesses, and unique demands. Knowing where each shines can help you choose the right weapon for your workouts.

Most Full-Body: Rower

“The rower recruits the most musculature of all three machines,” says DiPrimio. Every stroke engages the legs, hips, core, and upper body in an extended range of motion that few other cardio tools can match. The Assault Bike comes close, but rowing’s combination of power and total-body mechanics gives it the edge.

• Engages legs, hips, core, and upper body
• The most extensive total range of motion
• Close second: Assault Bike

Highest Cardio Demand: Assault Bike

The Assault Bike is notorious for breaking people down quickly. With no recovery phase, every push and pull drives heart rate and lactate levels sky high. DiPrimio notes it often “feels fine at first, then leaves you completely destroyed by the end.”

• Constant resistance, no built-in recovery
• Produces massive lactate spikes
• Rower close behind, SkiErg slightly lower

Best for Fat Loss: Any Machine You’ll Use Consistently

Here, DiPrimio emphasizes that the machine itself matters less than consistency. “It’s calories in versus calories out,” he explains. High-intensity bursts may torch calories in the moment, but sustainable results come from steady effort over weeks and months.

• Consistency matters more than calorie burn
• Pick the machine you’ll actually use
• Long-term adherence beats quick fixes

Best for Conditioning: Rower (With Assault Bike Close Behind)

For general fitness, the rower provides the most complete conditioning stimulus. The Assault Bike is nearly equal, but the SkiErg takes the cake for the best upper-body recruitment.

• Rower: Most balanced conditioning
• Assault Bike: Almost tied with the rower
• SkiErg: Upper-body dominant

Best for Intervals: Assault Bike | Best for Steady State: Rower/SkiErg

The Assault Bike thrives in short, brutal intervals. The rower and SkiErg, with their built-in recovery phases, are better suited to longer steady-state sessions. DiPrimio recommends mastering steady work on all three before layering in high-intensity intervals.

• Assault Bike: Short-HIIT king
• Rower: Versatile for steady or intervals
• SkiErg: best for upper-body endurance

Easiest to Learn: Assault Bike

Sit down, start pedaling, and you’re in. The rower and SkiErg both require more technical proficiency and pacing discipline to be effective and safe.

• Assault Bike: Plug-and-play
• Rower: Timing and sequencing matter
• SkiErg: Hinging mechanics matter

Best for Injury Considerations: SkiErg

For anyone dealing with lower-body injuries, the SkiErg is the most forgiving option, as it primarily targets the upper body. The rower can aggravate the lower back if the technique breaks down, while the Assault Bike can stress the knees.

• Upper-body focused, lower impact
• Rower: Potential low-back strain
• Assault Bike: Tough on knees

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Workouts & Progressions

Each of these machines can be a brutal tool for HIIT or a steady partner for long aerobic grinds. The key is knowing how to start, when to push, and how to build up intelligently. DiPrimio recommends starting with steady-state intervals to develop technique, efficiency, and baseline capacity before layering in high-intensity work.

Best for Beginners: Steady-State Progression

DiPrimio suggests a simple weekly build-up starting with one-minute work bouts and gradually increasing duration. This approach improves form, builds muscular endurance, and lays the aerobic foundation needed for more demanding sessions. By week four or five, you’ll be ready for longer, continuous sessions or higher-intensity intervals without burning out.

• Week 1: 10–15 x 1 min on / 1 min off
• Week 2: 10–15 x 2 min on / 1 min off
• Week 3: 8–10 x 3 min on / 1 min off
• Week 4: 6–8 x 4 min on / 1 min off
• Week 5: 4–6 x 5 min on / 1 min off → then progress to 20–45 min continuous

Best for HIIT: Assault Bike

The Assault Bike thrives for short, savage intervals. With constant resistance, even 20-second sprints feel devastating. DiPrimio notes it produces massive lactate spikes, so keep sessions brief and controlled. Tabata (20 seconds on, 10 seconds off) is a classic here, but even 30-second sprints with long recovery will leave you humbled.

• Short, max-effort bursts = best results
• Tabata (20:10) is a killer choice
• Keep HIIT sessions shorter than rowing or SkiErg

Best for Longer Intervals: Rower

The rower is versatile enough for both HIIT and steady-state training, but it excels in longer interval sets. Each stroke’s natural recovery phase makes extended work more sustainable compared to the bike. DiPrimio often programs 500m repeats or 2–3 minute intervals for conditioning athletes.

• Try 6 x 500m with 90 sec rest
• Or 8–10 x 2–3 min on / 1 min off
• Sustainable for steady builds or interval conditioning

Best for Upper-Body HIIT: SkiErg

The SkiErg can torch your arms, lats, and core, but it requires patience and dedication. New users often fatigue quickly in the upper body. DiPrimio advises starting slow, building endurance, and progressing into HIIT once the base is set. When you’re ready, short bursts of 30–60 seconds with full recovery can effectively target the upper body without overexerting the legs.

• Build endurance before hard intervals
• Start with short steady-state sessions
• Progress to 8–10 x 30–60 sec sprints with 60–90 sec rest

Verdict: The Right Tool for the Job

So, which machine deserves the title of man’s best friend in the gym? The truth is, all three deliver world-class conditioning when used consistently. The rower comes out on top in terms of overall muscle recruitment and balanced conditioning. The Assault Bike reigns supreme for short, high-intensity intervals that push your limits fast. The SkiErg fills a unique lane, torching the upper body and providing a lower-impact option when your legs need a break.

DiPrimio’s advice is simple: pick the machine you actually enjoy enough to use regularly. Consistency matters more than the calorie numbers you’ll see on the console. If you dread the bike, it won’t do much for your fitness sitting in the corner.

There’s also a bit of carryover between machines, but not equally. Getting fit on the rower or Assault Bike will give you a head start on the SkiErg, as both require more total musculature. The reverse isn’t as true: SkiErg endurance won’t translate as strongly to leg-dominant conditioning.

Bottom line: If you have access to all three, rotate them. If you only have one, lean into it and master it. You’ll build a strong engine, torch calories, and earn the conditioning benefits no matter which option you choose.