fitting different regressions for cyclic data

I have cyclic data as shown in the attached figure.

I amanged to define the minima and peak for each cylce

I would like to fit a regression for each cycle using Matlab. how can i do this?

this is what i have done so far:

%% data
close all
clear all
clc
data_org = importdata('N_trial.txt');
testname = sprintf('N_trial');
Time=data_org(:,1);
FV=data_org(:,2);
FH1=data_org(:,3);
FH2=data_org(:,4);
dV_raw=data_org(:,5);
dH1_raw=data_org(:,6);
dH2_raw=data_org(:,7);

ln = plot(Time, FV);set(ln, 'Color');
hold on

%input parameters
V_flex = 0.000001;     %Vertical flexibility factor
H1_flex = 0.048;    %Horizontal 1 flexibility factor


%calculate Displacement with correction of flexibility
dV_net = (dV_raw-V_flex*FV)*1000-85.64;

%% identify cycles
[pks,locs] = findpeaks(data_org(:,2),'MinPeakDistance',70);

% find minimum points(fatin)
FV_Inv = 1.01*max(FV) - FV
[Minima,MinIdx] = findpeaks(FV_Inv,'MinPeakDistance', 70);
Minima = FV(MinIdx);

%count_cycle= numel(findpeaks(your_signal))
count_cycle= numel(Minima);

Answer 1

[KSSV]

Read about polyfit. This will fit you striaght line/ curve for a given data (x,y).