BengalCat

I do a light upper body and lower body weight-workout for all-around tone and strength. It is good independently and also a good supplement to my cycling.

A question for those that exercise and have some math skills. I used a leg press machine in my workouts in the weight room. The sled has attachments to allow you to add weights. The sled and added weights ride on rails that I’m guessing are sloped upward 45 degrees. One lays on a slanted back support on the floor and then places their feet on the sled and from that position starts doing leg presses.

Question: How much if any does the 45-degree slant reduce the resistance of the combined weight of the sled and added weights.

I do two sets of 300 pounds in actual weight. Question: what is the functional or exercise weight of that three hundred pounds that moves up and down the rails? Is it significantly different, or the same, or are you functionally truly doing a 300-pound squat?

Unca_Sam

The hip sled isolates your quads and glutes from the minor groups that contribute to functional strength. You're right that the 45° angle reduces the total weight you're actually moving. Ballpark suggests that it's greater than 50% of the weight, but less than actually squatting 300. It's probably complicated since you need to figure friction, but it's solvable with vectors and trig.

Carbonfiberboy 

Well, you also have to add the weight of the sled itself, and different machines are very different in this regard. The only way to find the equivalent is by personal experimentation.

No, you are absolutely not doing a 300 lb. squat. I only squat now and it's been a long time since I sledded. Back when I did sets of 30 reps, IIRC, I squatted 135 and sledded 270. Which as I said, would only be valid for that machine and the 30 reps complicates the issue. Reps are a lot easier to knock out on the sled.

There's also the question of what squat? Full ATG, powerlifter squat, 1/2 squat . . .

I should also mention that I didn't push the squat but I did push the sled. I could have squatted maybe another 10 lbs.

Seattle Forrest

Leg Press

Leg Press is a machine where you push weight away with your feet. Some Leg Press machines are 45° incline, others are horizontal. But they’re never substitutes for Squats. The weight moves, you don’t. You don’t balance the weight, the machine does. Go too deep and your lower back will round at the bottom and squeeze your spinal discs. Unless you have no arms to hold the bar on your back, stick with free weight Squats.

https://stronglifts.com/squat/#Leg_Press

He's overplaying his hand a little - there isn't just one right way - but there's truth in what he's saying. Also, the spine part.

wolfchild

Nothing compares to a full squat done below parallel or at least down to a parallel. Leg press is a completely different exercise and doesn't load and stress the body in the same way as the squat...Not everybody is made to do squats, if for any reason you can't do proper squats, then a leg press is a next best alternative. If you can't squat at least down to a parallel, then you're not made for squats and you need to find an alternative, don't waste your time with half-squats or quarter squats.

BengalCat

The 300-pound figure includes the weight of the sled. Yes, I know that the actual resistance on my leg press isn't functionally 300 pounds because of the angle of the sled rails. I thought perhaps some math person could figure out what the actual weight or resistant was on the leg press assuming an estimated 45-degree angle of the rails

The machine has the capacity to add up to 1440 pounds of plates. The most I've personally seen someone add is 720 pounds of plates, and that's not too often.

My knees and some other bio-mechanics or joint issues won't allow me to do any conventional squats but this particular sled design doesn't bother my knees one bit. In that sense, it is a wonderful device. It is totally comfortable and safe.

This leg press machine model or design is far and away the most comfortable that I've encountered in several decades. Very stable, comfortable, and adjustable to the individual height of the person using it. seat and back design are ergonomically perfect so you get a good workout for the entire leg, especially the upper leg.

Unca_Sam

Why would we rob you of an opportunity to learn a thing or two?

Marylander

You could do "perfect world" math but there's more to it than just the 45deg angle (for instance, how smooth the bushings are). I've used a few 45deg leg press machines and they're all a little different. There's no real point to figuring out some 'precise' number. Just figure out what weight you need on the machine to do the workouts you're doing. If you get on another one you'll almost certainly have to make some adjustments, whether big or small.

OBoile

On a 45 degree incline, you're doing roughly 70% of the weight. It's high school trig. The sine of 45 degrees is .707.
https://www.rapidtables.com/calc/mat...alculator.html

aclass

As someone who once had ambitions of body building but now a much lighter cyclists, I doubt very seriously there is a cyclists alive who can legitimately squat 300lbs. Quite frankly, there arent too many non-cyclists who can.

Unca_Sam

While there's a kernel of truth to this, lets add perspective. When I was younger and had more time, I was my brother's training partner for the summer before he entered a D3 college football program. It was a basic training regimen for strength, and it took me a good 12 weeks to get up to 275 from an above average overall fitness level. I'll bet the reason there aren't many people who can squat 300 lbs is because they don't have to and it's a lot of work to get there. There's probably a lot of people that can't complete a mile running (no walking), because they don't have to, etc.

OBoile

Here's Jasper Verkuijl front squatting 265x4 after he'd already deadlifted. I'm pretty sure he could hit a 300 lb back squat without too much trouble.

A 300 lb squat isn't that big of a deal. I've hit 400 myself (although I wasn't a cyclist then) and, as you can see, I wasn't exactly huge or particularly good at powerlifting.

Seattle Forrest

Did you mean bench or overhead press? Squatting 300 lbs isn't that big a deal. And while roadies have a reputation for being slight, that doesn't apply so much to mountain bikers.

aclass

Okay! I take it back. But with all due respect, getting under 300lbs with a free bar and performing a legite squat is quite the big deal to me. 4 plates is epic, 3 plates is still out of touch for most.

BengalCat

My knowledge of trigonometry is zero. Thanks for the info.

Marylander

I'm betting there are lots and lots of track cyclists squatting well over 300. I would like to be a bit more inclined to aerobic power myself as I'm on the other end of the spectrum. I can easily squat 300+ (was up to 2x515 when I was powerlifting) but making any kind of watts for an extended period of time is outside of my wheelhouse. As a runner I could barely break 2 hours in the half marathon...

OBoile

I will agree with you that it's pretty rare to see a 300 lb squat to respectable depth in the gym. It is very good. But it's also a matter of perspective. What's considered very good compared to the general population is not anywhere near what is good compared to people who compete at a high level. If you can run a 40 minute 10k, you're faster than ~95% of people that join local races, but the elite people are finishing 3 km ahead of you. I've got a roughly 3.7 watts/kg right now which makes me pretty fast compared to most people I see on the bike trail, but put me in a cat 1 (or even cat 2 or 3) race and I'm going to get destroyed.

When I lifted seriously, I'd get stared at in local gyms (my wife would get stared at even more as she was considerably better than me) a lot. Then I'd go train with a powerlifting team and be one of the weaker guys there (and likely would be the weakest if it weren't for people in their 60s and 70s still lifting). The contest video I posted above was, IIRC, about 30 kg short of qualifying for my provincial championships that year. Had I been able to qualify (I had in previous years, then they raised the requirement) I would have lost by at least 100 kg.

Unca_Sam

It's the same story over and over: "No matter how fast/strong/big/mean you are, there's always someone 'X'-er than you".

OBoile

That's true. Very true. But it's also just a case of how seriously people take things. Lots of people go out and ride their bikes. A significant amount do >100 km a week on group rides and the like. But even among these people, only a minority are following a dedicated training program with the goal of driving their power up, and even fewer happen to do it year in and year out over an extended time period. Lots of people *exercise* at the gym (or on the bike), not many *train* and you see a significant difference in the results between the two groups.

wolfchild

There are track cyclists out there who can squat over 500 pounds, some of them are very muscular and strong and they do some serious weightlifting as part of their training....I agree with you about the part that there aren't too many people who can squat that much, majority of people are doing half squats and quarter squats which shouldn't even be called squats. Very few people have the mobility to go below parallel or even parallel. A squat is not a squat unless it's done at least down to parallel.