A single USPS package tops out well below most boxed gym equipment

Maximum length plus girth in inches; no mailpiece may weigh more than 70 pounds

USPS size limits for a single package No USPS mailpiece may measure more than 108 inches in length and girth combined, or 130 inches for USPS Ground Advantage retail, and none may weigh more than 70 pounds. Most mailpieces, length plus girth · 108 inches Most mailpieces, length plus girth 108 inches Ground Advantage retail, length plus girth · 130 inches Ground Advantage retail, length plus girth 130 inches

Source: United States Postal Service, Domestic Mail Manual 101