電肌肉刺激（EMS）技術自19世紀初商業化以來歷經起伏，如今廣泛應用於復健醫療及體能訓練領域。其原理是在運動時透過電脈衝刺激肌肉，短時間內產生數千次肌肉收縮，遠超傳統訓練所能達到的次數。目前市面上已有多家公司推出家用EMS訓練衣，其中德國品牌Pepper以1,400美元的價格提供最平價的選擇，號稱穿著該套裝運動20分鐘即可達到傳統一小時訓練的熱量消耗與肌肉激活效果。
針對EMS的科學研究結果喜憂參半但整體偏向樂觀。2021年一項統合分析發現EMS對肌肉量與力量有顯著正面效果，但對體脂肪減少無明顯幫助；2023年的研究則指出，八週持續阻力訓練結合每日EMS可顯著增加肌肉量並降低體脂率。然而醫學界對此尚未形成共識：有醫師認為EMS主要適用於復健患者，也有NFL隊醫將其納入自身訓練輔助，多數專家建議將EMS視為傳統力量訓練的補充而非替代。
作者親身穿著Pepper套裝進行了為期兩個月、每週三次的測試體驗。過程中他發現汗水會大幅影響導電性進而改變刺激強度，腹部肌肉對電擊最為敏感，且套裝的應用程式偶有故障。兩個月後，數據顯示他增加了2.7磅肌肉、減少了1.6磅脂肪，手臂、大腿和胸圍各增加半吋以上，力量也有所提升，但腰圍未見改善。作者認為EMS確實對其體能產生了一定正面影響，計劃繼續使用但將頻率降至每週兩次。
Electrical muscle stimulation (EMS) has been commercially available since the early 19th century and is now used in both rehabilitative medicine and fitness training. The technology works by delivering electrical pulses to muscles during exercise, generating thousands of contractions far beyond what traditional repetitions can achieve. Several companies now offer home-use EMS suits, with German brand Pepper providing the most affordable option at $1,400, claiming that a 20-minute suited workout equals an hour of conventional exercise in caloric burn and muscle activation.
Scientific research on EMS is extensive but mixed, though generally optimistic. A 2021 meta-study found significant positive effects on muscle mass and strength but not on body fat, while a 2023 study showed that eight weeks of resistance training combined with daily EMS significantly improved muscle mass and reduced body fat percentage. Medical opinions range widely: some physicians see EMS as beneficial mainly for rehabilitation patients, while others, including an NFL team doctor, incorporate it into their own training. The prevailing expert consensus is that EMS should complement traditional strength training rather than replace it.
The author tested the Pepper suit over two months with three sessions per week alongside his regular exercise routine. He discovered that sweat dramatically affects electrical conductivity and shock intensity, that abdominal muscles are especially sensitive to stimulation, and that the app occasionally glitched. After the trial period, his data showed a gain of 2.7 pounds of muscle, a loss of 1.6 pounds of fat, increases of half an inch or more in biceps, thigh, and chest circumference, and modest strength improvements, though his waistline remained unchanged. He concluded that EMS likely contributed positively to his fitness gains and plans to continue using the suit at a reduced frequency of twice per week.