title: Silk peptide treatment can improve the exercise performance of mice.
abstract: BACKGROUND
  We previously reported that silk peptide (SP) treatment led to increased resting fat oxidation in exercised mice. However, it was not known whether SP treatment could effectively increase exercise capacity. Accordingly, this study aimed to examine whether SP treatment affected energy metabolism during exercise in addition to exercise performance.
  
  
  METHODS
  We randomized 36 7-week-old male ICR mice into 2 groups: the control (n = 18) and SP (n = 18) groups. All mice were trained by treadmill running 5 times per week for 2 weeks. SP was dissolved in distilled water and daily 800-mg/kg body weight doses before the running exercise were oral administered intraperitoneally to the SP group for 2 weeks. [Formula: see text] was measured before and after the 2 weeks training period. We also assessed energy metabolism during exercise for 1 h after the 2 week training period. In addition to blood samples, liver glycogen and gastrocnemius-white and gastrocnemius-red muscle was obtained at the following 3 time points: at rest, immediately after exercise, and 1-hour post exercise.
  
  
  RESULTS
  The [Formula: see text] max after 2 weeks of training was significantly increased (8%) in the SP group compared to the baseline; a similar result was not observed in the CON group. The sum of fat oxidation during a 1-h period tended to be 13% higher in the SP group than in the CON group (P < 0.077). In particular, the sum of fat oxidation was significantly higher in the SP group during the initial 20-min phase than that in the CON group (P < 0.05). The glycogen concentration in the white gastrocnemius muscle did not differ between the groups either rest or after 1 h of exercise but was significantly higher in the SP group than in the CON group during the recovery period (1 h post-exercise completion).
  
  
  CONCLUSIONS
  These results suggest that SP treatment can improve the exercise performance. Therefore, SP is considered to confer beneficial effects upon athletes, in whom exercise abilities are required.
authors: Laboratory of Exercise Nutrition, Department of Physical Education, Konkuk University, 120, Neungdong-ro, Gwangin-gu, Seoul 143-701, Republic of Korea.
authors: Jisu
authors: J
authors: Kim
authors: Laboratory of Exercise Nutrition, Department of Physical Education, Konkuk University, 120, Neungdong-ro, Gwangin-gu, Seoul 143-701, Republic of Korea.
authors: Hyejung
authors: H
authors: Hwang
authors: Laboratory of Exercise Nutrition, Department of Physical Education, Konkuk University, 120, Neungdong-ro, Gwangin-gu, Seoul 143-701, Republic of Korea.
authors: Jonghoon
authors: J
authors: Park
authors: Laboratory of Exercise Nutrition, Department of Physical Education, Konkuk University, 120, Neungdong-ro, Gwangin-gu, Seoul 143-701, Republic of Korea.
authors: Hea-Yeon
authors: HY
authors: Yun
authors: Laboratory of Exercise Nutrition, Department of Physical Education, Konkuk University, 120, Neungdong-ro, Gwangin-gu, Seoul 143-701, Republic of Korea.
authors: Heajung
authors: H
authors: Suh
authors: Laboratory of Exercise Nutrition, Department of Physical Education, Konkuk University, 120, Neungdong-ro, Gwangin-gu, Seoul 143-701, Republic of Korea.
authors: Kiwon
authors: K
authors: Lim
keywords: Energy metabolism during exercise; Exercise performance; Fat oxidation; Silk peptide