DOI: 10.5061/dryad.ttdz08mbb
title: Paternal physical inactivity alters offspring sex ratio and is associated with heritable impairments in reproductive success in rats

description: Paternal lifestyle factors are increasingly recognized as determinants of
 offspring health, yet the effects of physical inactivity on reproduction
 remain unclear. Here, we demonstrated that paternal physical inactivity
 caused a bias in offspring sex ratio and reduced fertility across
 generations in rats. Male rats subjected to 8 weeks of restricted activity
 produced offspring with a female-biased sex ratio (female:male = 39:16; p
 = 0.011; odds ratio = 2.84) compared with controls (24:28). Sperm motility
 was markedly reduced in inactive fathers (p &lt; 0.001 vs. control)
 but was fully restored by voluntary wheel running (p &lt; 0.05 vs.
 inactive), indicating reversibility of this functional impairment.
 Cross-mating of first-filial-generation (F1) rats of inactive paternal
 origin revealed that females derived from inactive fathers exhibited lower
 pregnancy rates and smaller litter size, whereas F1 males displayed normal
 fertility. Remarkably, intercrosses between F1 males and females of
 inactive paternal origin produced no viable offspring surviving to weaning
 age. Although the sample size was limited, this outcome suggests a
 heritable impairment in reproductive success. These findings identify
 paternal physical inactivity as an environmental factor influencing
 offspring sex ratio and reproductive success across generations; however,
 studies with larger mating cohorts are needed to confirm this
 transgenerational phenotype.
description: # Paternal physical inactivity alters offspring sex ratio and is
 associated with heritable impairments in reproductive success in rats
 Dataset DOI:
 [10.5061/dryad.ttdz08mbb](https://doi.org/10.5061/dryad.ttdz08mbb) ##
 Description of the data and file structure Raw data supporting Yoshihara
 et al., Biology Letters, RSBL-2025-0725 ### Files and variables #### File:
 Supplementary_Table_1_F0_mating.xlsx **Description:** Each row represents
 one breeding pair. Data include sire and dam IDs, group allocation
 (Control or Inactive), cohabitation period, pregnancy confirmation, litter
 size, sex ratio (female:male), and fraction of male pups (male/total).
 Statistical analyses are described in the Materials and Methods section.
 ##### Variables * Group, No., Sire ID, Sire group, Dam
 ID, Cohabitation, Pregnancy confirmation, Litter size, Weaning
 survival, Female : Male, Fraction male pups #### File:
 Supplementary_Table_2_F1_cross.xlsx **Description:** Each row represents
 one mating pair. Columns include sire and dam IDs, paternal background
 (C-derived or I-derived), cohabitation period, pregnancy status, litter
 size, and offspring survival at weaning. No statistical analyses were
 performed due to limited sample size. ##### Variables * Group, No., Sire
 ID, Sire group, Dam ID, Cohabitation, Pregnancy confirmation, Litter
 size, Weaning survival, Female : Male, Fraction male pups #### File:
 Supplementary_Table_3_Sperm_motility.xlsx **Description:** Each row
 represents one sire. Columns include group (Control, Inactive,
 Inactive+Exercise), percentage of motile sperm, and kinematic parameters
 derived from SMAS analysis: VAP (average path velocity), VSL
 (straight-line velocity), VCL (curvilinear velocity), LIN (linearity =
 VSL/VCL ×100), STR (straightness = VSL/VAP ×100), ALH (amplitude of
 lateral head displacement, µm), and BCF (beat-cross frequency, Hz). All
 parameters were recorded under identical settings (frame rate = 60 Hz,
 calibration = 0.627 µm/pixel, tracking &gt;= 60 frames). ##### Variables *
 No., Rat ID, Group, %Motile, VAP μm/s, VSL μm/s, VCL μm/s, LIN, STR, ALH
 μm, BCF Hz ## Code/software Excel ## Access information Other publicly
 accessible locations of the data: * No other publicly accessible
 locations. Data was derived from the following sources: * Not applicable.