Don't know why, perhaps due to rising demand and production bandwidth, but be forewarned quality control is an issue. Assembly is easy enough, though have gap where back separator does not fit snugly after tightening nuts as firm as they will go (see pic). No water level sticker on tank received, so had to measure water manually according to calculations (4 gallons). Siphon was not air tight (even though release valve closed firmly), so had to manually pump instead of siphon. S4 monitor only flashes, not working as of yet and now have to take a apart top of unit to figure out why, currently not resolved after verifying connections and looking at simple solutions on website.
According to Men’s Total Fitness, rowing machines are not only great for aerobic workouts, but they also work all of your body's major muscle groups. What’s more, you don’t have to go to the gym to work out on a rowing machine, as many manufacturers make high-quality rowing machines -- and even rowing machines that fold up for easy storage -- that are suitable for home use. Two popular types of rowing machines are the water rower and the air rower.
Rowing is primarily a cardio workout, but it’s also more than that. Your heart rate is absolutely going to be climbing, but unlike a jog in the park, you might also be sore the next day. The rower requires you use your legs more than anything, and as we know, your quads, glutes, calves, and hamstrings are the biggest, most powerful muscles in your body. But you’re also pulling with your arms, shoulders, abs and engaging your back. That said, you’re not pulling as hard as you might with, say, a seated cable row machine at the gym. You don’t want to hurt your back, but you can engage them and this will help you get those muscles toned.
From a fitness perspective, the WaterRower Natural works 84 percent of your muscle mass, helping tone and strengthen your muscles while burning far more calories than most other aerobic machines. The exercise is also low impact, as it removes all the body weight from the ankles, knees, and hips, but still moves the limbs and joints through a full range of motion--from completely extended to completely contracted.