I did V-Sit Cross Jabs every day for a week — here’s what happened to my abs

a photo of a man with strong ab muscles
(Image credit: Shutterstock)

I hate training my core. It's boring and I'd much rather be out with one of the best running watches or lifting heavy with the best adjustable dumbbells. But, when it comes to exercise, a strong core is one of the best things you can develop for your overall health. Strong abdominals leads to better posture, heavier lifting and a faster lap time.

In fact, research has shown a healthy core can alleviate chronic lower back pain and help protect athletes from developing such problems in the first place.

So, with trepidation, I took on an ab workout challenge in the best traditions of the Tom's Guide fitness team. Although we've done a great number of planks and rollouts in our search for the best ab exercises out there, I wanted to build in a little strength training too.

I settled on the v-sit cross jab, which is a hybrid movement that works a few different muscle groups at the same time. It meant that while I was training my six-pack muscles, I was also working the oblique muscles down the side and my shoulders. I prefer compound over isolated exercises anyway because I'm forever short of time, so this appealed to me.

Read on to find out how to do a v-sit cross jab properly, as well as what happened to me after I tried incorporating it into my exercise routine for a week.

As a reminder, go easy if you're returning to exercise after a prolonged period or taking it up for the first time. It's always useful to talk to a personal trainer before engaging in some exercises, especially if they involve a challenging weightlifting element. It’s also not recommended to train your abdominal muscles every single day, as your body needs time to rest and recover.

How to do v-sit cross jabs

Sitting punches exercise

(Image credit: Shutterstock)

You can do v-sit cross jabs with just your bodyweight and still work your core. But if you want to add progressive overload, it's worth grabbing a set of the best adjustable dumbbells or strapping on some wrist weights to increase the challenge. 

V-sit jabs exercise

(Image credit: Shutterstock)
  • Start by sitting on your exercise mat with your feet on the floor and your knees bent.
  • Lean your upper body back and bring your feet slowly up off the floor. Your upper body should be at a 45-degree angle with the floor so that, together with your legs, you form a V-shape.
  • Hold a dumbbell in each hand (or a closed fist if you're not using weights) with your palms facing inward. They should be tucked in close to your chest, with your elbows bent.
  • Engage your abs and extend your left arm out and slightly across your body, making sure to keep your body in the V-shape. Keep the jab slow and controlled as you bring the weight (or fist) back to its starting position.
  • Do the same thing with the right hand.
  • Your torso and shoulders may naturally rotate with the direction of the jab, this is fine  but the key is to keep your body in the V-shape and stop your legs from wobbling.
  • A jab with each hand counts as one repetition. Repeat the process for the number of reps you're trying to get to.

One of the benefits of this exercise is, like the Russian Twist, it strengthens your core as well as your upper body muscles. In this case, it's your shoulders that will feel the strain. But you'll be honing the deep stabilizing muscles in your hips, trunk and glutes too. As an aside, here's what happened when our fitness writer did 50 Russian twists every day for a week.

I did V-Sit Cross Jabs for a week — here are my results  

To be transparent up front; I didn't expect any visible changes to my midsection after just a week of doing these exercises. If you're gunning for a visible six-pack, you'll need to take into account a balanced diet and cardio to lower your overall body fat percentage. If you're interested, here’s how to calculate your body fat percentage, and why it matters

What I was looking for was a quick-fire exercise that I could tack on to a workout to strengthen my core without getting bored by it. Shadowboxing to music is a great way to drip a sweat, so I was hoping to get some of the same benefits here. And, as it happened, it was actually more fun than I was expecting. Here’s my training diary from the week: 

Day 1

Since this was my first attempt at one of these challenges, I went easy. Super easy, as a matter of fact. No weights and a mere 30 reps to test the boundaries. To be honest, this was more a case of getting my form in good order: feet not too far off the ground, core tensed, jabs smooth and controlled.

While the lack of weight meant I didn't give my shoulders anything to worry about, even this ridiculously small set left me with a twinge of resistance in my abs. Like I said: despite all the best advice, I don't really train my core.

I did like the mental focus of working two muscle groups (abs and shoulders) at the same time. And the fact I was doing it bodyweight-only meant it could theoretically be done anywhere - out on a run, for example. I vowed to add weights and up the reps the next day.

Days 2 & 3

Things got a bit more real today. I grabbed two of the Ativafit adjustable dumbbells to add weight to my jabs, and upped the rep count to 60, broken down into two sets of 30.

Immediately the added weight started to punish not just my shoulders but also my forearms as I tried to keep my arms level. I opted for a 5KG (11lbs) weight which, realistically, is about all I can manage while keeping my form on point.

It was particularly challenging to keep my torso rigid and my legs a steady height off the ground while making allowances for the weight of the dumbbells. By the end of the two sets, especially on day 3, I was breathing hard and my arms were aching.

Day 4

On day four of the challenge, I chickened out of using the weights and just went back to clenched fists. The reason was twofold: first, I was running short on time and second, there was definitely some delayed onset muscle soreness (DOMS) in my arms.

So, taking it easy was the aim of the game but I did decide to tack on an extra set and bring my total number of v-sit cross jabs up to 90. I concentrated hard to make sure my core was taking the brunt of it and, when it was time to finish, I could feel the effects. 

When it comes to selecting the right weight for an exercise, it’s important to ensure it isn’t compromising your form. If it's a case of dropping the weight altogether to go back to basics once or twice, that's fine too. Don't be a hero.

Day 5

By day five, I'd settled into the groove and went back to using the dumbbells. Despite the urge to drop down to 3KG, I kept to 5 and powered through. But I still only managed 60 before needing to take a breather. I still hadn't mastered total form with this exercise and had to catch myself from holding my breath instead of a slow steady exhale during the jab.

The breakthrough I had today was to do the exercise in front of a mirror so I could keep an eye on how my body was holding its position during each of the jabs and adjust accordingly.

Days 6 and 7

I'll be honest, I was starting to get bored at this point. Just for a laugh, I loaded up my adjustable dumbbells with 11KG (24lbs) on each arm to see what would happen. The result? I couldn't even manage five jabs before my arms sagged to the floor.

Suitably chastened, I resumed my 5KG weights and aimed for 90 reps, broken down into three sets of 30 with a 30-second rest between each set. On both days, this was enough to leave my forearms and shoulders begging for mercy and nicely raised heart rate.

Interestingly, my abs weren't as punished as my arms were and I think it's because the addition of the weight simply pulled my focus away from my core and towards the dumbbells. Either way, by the end of the last day I was convinced I'd got a solid workout and mastered a move that I could now add to my repertoire. I'd like to gradually increase weight going forward, providing it doesn't compromise form.

How did my abs look after the end of the challenge? Sad to say: no different from the start. A week isn’t long enough to notice any visible difference in the body — sadly, building muscle takes a lot longer. And while this whole thing hasn't really made me enjoy training my core any more than I did a week ago, I'd still recommend giving it a go yourself. Even if it's just to change things up a little bit in your own fitness journey.

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Jeff Parsons
UK Editor In Chief

Jeff is UK Editor-in-Chief for Tom’s Guide looking after the day-to-day output of the site’s British contingent. Rising early and heading straight for the coffee machine, Jeff loves nothing more than dialling into the zeitgeist of the day’s tech news.


A tech journalist for over a decade, he’s travelled the world testing any gadget he can get his hands on. Jeff has a keen interest in fitness and wearables as well as the latest tablets and laptops. A lapsed gamer, he fondly remembers the days when problems were solved by taking out the cartridge and blowing away the dust.