Article continues below advertisementRyan Seacrest wasn't shy about showing off his physique, flexing for the 'gram in cheeky photos a few months after fans raised concerns about his slimmer look."Between a rock and a hard plank. Best gym on Earth... literally. Happy #EarthDay 🌎," Seacrest, 51, captioned a throwback photo of himself hitting core-strengthening crunches on the beach.